Réunion plénière du GDR 3732 «...

Réunion plénière du GDR 3732

« MEETICC » Matériaux Etats ElecTronIques Interactions

et Couplages non Conventionnels

Organisateurs: Sébastien Burdin & Andrés Cano Secrétaire : Marie-France Mariotto Directeurs : Pascale Foury & Etienne Janod

LATRESNE 28-31 mars

2017

Comité d’organisation

CANO Andres, Institut de Chimie de la Matière Condensée de Bordeaux BURDIN Sébastien, Laboratoire Ondes et Matière d'Aquitaine, Bordeaux FOURY Pascale, Laboratoire de Physique des Solides,Orsay JANOD Etienne, Institut des Matériaux Jean Rouxel, Nantes Secrétariat : MARIOTTO Marie-France, Laboratoire de Physique des Solides, Orsay

Conseil Scientifique du GDR

BERGEAL Nicolas, École Supérieure de Physique et de Chimie Industrielles de Paris BERT Fabrice, Laboratoire de Physique des Solides (Orsay) BIBES Manuel, UMR CNRS-Thalès (Palaiseau) BORDET Pierre, Institut Néel (Grenoble) BRISON Jean-Pascal, CEA – Grenoble, Service de Physique Statistique, Magnétisme et Supraconductivité BRUN Christophe, Institut des NanoSciences de Paris BURDIN Sébastien, Laboratoire Ondes et Matière d’Aquitaine (Bordeaux) CARIO Laurent, Institut des Matériaux Jean Rouxel (IMN, Nantes) COLSON Dorothée, CEA-Saclay, Service de Physique de l’Etat Condensé CREN Tristan, Institut des NanoSciences de Paris DAMAY Françoise, Laboratoire Léon Brillouin, CNRS-CEA-Saclay D’ASTUTO Mattéo, Institut de minéralogie, de physique des matériaux et de cosmochimie (Paris) DE CARO Dominique, Laboratoire de Chimie de Coordination (Toulouse) DUC Fabienne, Laboratoire National des Champs Magnétiques Intenses (Toulouse) FOURMIGUE Marc, Institut des Sciences Chimiques de Rennes GEORGES Antoine, Collège de France (Paris) LE BOLLOC’H David, Laboratoire de Physique des Solides (Orsay) LOBO Ricardo, École Supérieure de Physique et de Chimie Industrielles de Paris LORENC Maciej, Institut de Physique de Rennes MEASSON Marie-Aude, Laboratoire Matériaux et Phénomènes Quantiques (Paris) MIREBEAU Isabelle, Laboratoire Léon Brillouin, CNRS-CEA-Saclay PAUTRAT Alain, Laboratoire de Cristallographie et Science des Matériaux (CRISMAT, Caen) PETIT Sylvain, Laboratoire Léon Brillouin, CNRS-CEA-Saclay PINSARD Loreynne, Institut de Chimie Moléculaire et des Matériaux (ICCMO, Orsay) POILBLANC Didier, Laboratoire de Physique Théorique (Toulouse) PONS Stéphane, École Supérieure de Physique et de Chimie Industrielles de Paris RABU Pierre, Institut de Physique et de Chimie des Matériaux de Strasbourg RALKO Arnaud, Institut Néel (Grenoble) ROZENBERG Marcelo, Laboratoire de Physique des Solides (Orsay) SACUTO Alain, Laboratoire Matériaux et Phénomènes Quantiques (Paris) SCOLA Joseph, Groupe d’Etude de la Matière condensée (GEMAC, Versailles) SIDIS Yvan, Laboratoire Léon Brillouin, CNRS-CEA-Saclay SIMONET Virginie, Institut Néel (Grenoble) TA PHUOC Vinh, GREMAN (Tours) THIAVILLE André, Laboratoire de Physique des Solides (Orsay)

Programme

mardi 28 mars 2017

14:00 - 14:15 Introduction 14:30 - 15:55 Supraconductivité I - Chairman: Luca de' Medici

14:30 - 15:10 › Colloque - Emerging symmetries and the pseudo-gap state of the cuprates - CatherinePépin, Institut de Physique Théorique (ex SPhT)

15:10 - 15:25 › Evidence for hidden fermions and unconventional pairing in high-temperaturesuperconducting cuprates - Marcello Civelli, Labortoire de Physique des Solides

15:25 - 15:40› High temperature superconducting oxychlorides: a light element model for cuprates. - Matteo D'Astuto, Institut de minéralogie, de physique des matériaux et de cosmochimie - Blair Lebert,Institut de minéralogie, de physique des matériaux et de cosmochimie

15:40 - 15:55 › Evolution of spectral functions and transport quantities with doping in the SU(2) theory of cuprates. - Corentin Morice, Institut de physique théorique, CEA Saclay

15:55 - 16:30 Pause 16:30 - 17:10 Supraconductivité I - Chairman: M. d'Astuto

16:30 - 16:55 › Focus - Fermi surface instabilities in ferromagnetic superconductors - alexandre pourret,Institut Nanosciences et Cryogénie

16:55 - 17:15 › Les cuprates à haute Tc, voix de chimistes - Michel Pouchard, ICMCB 17:15 - 17:55 Nouveaux matériaux - Chairman: M. Pouchard

17:15 - 17:55› Colloque - Stabilizing several anions (F, O, OH, S) in the vicinity of transition metals or rare earths to tune the optoelectronic properties of new materials - Alain Demourgues,ICMCB-CNRS

17:55 - 19:30 Poster › Revealing the complex band structure of LaAlO3/SrTiO3 interface by high magnetic field quantum transport - Ming Yang, Laboratoire national des champs magnétiques intenses - Toulouse - Michel Goiran, Laboratoire national des champs magnétiques intenses - Toulouse › Redox reactions induced by metals at the (100) and (111) surfaces of SrTiO3 probed by secondary ion mass spectroscopy - Joseph Scola, Groupe d'Etude de la Matière Condensée › Enhancement of superconductivity near the lattice-coupled nematic quantum critical point - Dimitri Labat, Matériaux et Phénomènes Quantiques › Search of new unconventionnal superconductors: the case of Cr based compounds - PierreToulemonde, Institut Néel › Comportement exotique des vortex dans un supraconducteur conventionel: le Niobium - AlainPautrat, Laboratoire de cristallographie et sciences des matériaux › Diagramme de phase magnétique de CePt2In7 par chaleur spécifique sous champs magnétiques intenses - Albin DE MUER, Laboratoire national des champs magnétiques intenses - Grenoble › Densités de charge et de spin experimentales de la perovskite YTiO3 obtenues par affinement joint - Nicolas Claiser, Laboratoire de Cristallographie, Résonance Magnétique et Modélisations › Nature de l'ordre orbital dans une perovskite magnétique: nouvelle méthode multitechnique - Beatrice Gillon, Laboratoire Léon Brillouin › Experimental charge and spin densities of the p-O2NC6F4CNSSN radical using joint refinement method - Ariste Voufack, Laboratoire de Cristallographie, Résonance Magnétique et Modélisations › Molecular Magnets: From the single molecule to the 3D self-assembly - Danilo Longo, Institut des Nanosciences de Paris › Hematite/Ilmenite (FeTiO3)-(Fe2O3) superlattices by PLD : new magnetic and transport properties - Yves Dumont, Groupe d'Etude de la Matière Condensée › Template synthesis and characterization of Bi2Te3 and Sb2Te3 nanowires - Rashmi Rani,Laboratoire des Solides Irradies, Ecole Polytechnique, Palaiseau, France - Marcin Konczykowski, Laboratoire des Solides Irradies, Ecole Polytechnique, Palaiseau, France › Nanocrystalline Nickel Synthesis by Pulsed Current - boukhouiete amel, university ob badji-mokhtar › Study of organic polluant degradation by advanced processes - Zahia BENREDJEM, Zahia BENREDJEM

mercredi 29 mars 2017

08:45 - 09:25 Colloque special Transitions et phases topologiques - Chairman: D. Carpentier

08:45 - 09:25 › Colloque - Quelques propriétés extraordinaires de la physique à deux dimensions -Jacques Villain, Institut Laue Langevin, Académie des Sciences

09:25 - 10:35 Magnétisme I - Chairwoman: M.-B. Lepetit 09:25 - 10:05 › Colloque - Frustration, chirality, multiferroism - Virginie Simonet, Institut Néel

10:05 - 10:20› Interplay between charge transfer and magnetic transition in the quadruple perovskite (YMn3)Mn4O12 - Marine Verseils, Institut de minéralogie, de physique des matériaux et de cosmochimie

10:20 - 10:35› Field-induced quasiparticles driving the quantum phase transition in Ising-like antiferromagnetic spin chain - Quentin FAURE, Institut Néel, Institut Nanosciences etCryogénie (ex DRFMC), Université Grenoble Alpes

10:35 - 11:00 Pause café 11:00 - 12:10 Magnétisme I - Chairwoman: I. Mirebeau

11:00 - 11:25 › Focus - Deux articles intéressants - Mario Maglione, Institut de Chimie de la MatièreCondensée de Bordeaux

11:25 - 11:40 › Pressure induced multiferrocity in PrMn2O5 - Wei Peng - Laboratoire de Physique desSolides

11:40 - 11:55 › Chiral spin liquid on kagome antiferromagnet induced by Dzyaloshinskii-Moriyainteraction - Laura Messio, Laboratoire de Physique Théorique de la Matière Condensée

11:55 - 12:10 › Emergent phenomena in spin liquids - Ludovic D.C. Jaubert, Laboratoire Ondes etMatière d'Aquitaine

12:10 - 14:00 Déjeuner 14:00 - 15:50 Techniques avancées - Chairman: D. Le Bolloc'h

14:00 - 14:40› Colloque - Techniques spectroscopiques avancées pour l'étude des systèmes corrélés. - Jean-Pascal Rueff, Synchrotron SOLEIL, Laboratoire de Chimie Physique - Matière et Rayonnement

14:40 - 15:05 › Focus - Sonder et impacter les matériaux aux échelles de temps ultra-rapides - EricCollet, Institut de Physique de Rennes

15:05 - 15:20 › Time-resolved X-ray Diffraction on Density-Waves systems - Sylvain RAVY,Laboratoire de Physique des Solides

15:20 - 15:35 › Collective transport of charges in charge density wave sytem based on traveling solitonlattices - Ewen Bellec, Laboratoire de Physique des Solides

15:35 - 15:50 › Three-dimensional critical phase diagram of a heavy-fermion Ising antiferromagnet -William Knafo, Laboratoire national des champs magnétiques intenses - Toulouse

15:50 - 16:15 Pause 16:15 - 17:25 Nouveaux matériaux - Chairman - L. Cario

16:15 - 16:40 › Focus - Multiferroics: What now? - Nathalie Viart, Institut de Physique et Chimie desMatériaux de Strasbourg

16:40 - 16:55 › AMnGe2O6 (A = Ca or Sr) : effet de la nature du cation divalent dans la structurepyroxène - Celine Darie, INSTITUT NEEL

16:55 - 17:10 › Rb2Ti2O5: quand un diélectrique n'est pas un isolant... - Brigitte Leridon, Laboratoire dePhysique et d'Étude des Matériaux

17:10 - 17:25 › Toward a gated FET on the basis of spin-transition polymers – Serguei Andreev,Laboratoire Ondes et Matière d'Aquitaine

17:30 - 17:45 Présentation de l'Ecole du GDR 2018 – M. D'Astuto. 17:45 - 19:30 Poster

jeudi 30 mars 2017 09:00 - 10:35 Magnétisme II - Chairwoman: C. Lacroix

09:00 - 09:40 › Colloque - Frustration, quantum magnetism and spin liquids - FABRICE BERT,Laboratoire de Physique des Solides

09:40 - 10:05 › Focus - Systèmes artificiels, systèmes modèles - Benjamin CANALS, Institut Néel

10:05 - 10:20 › Défauts topologiques dans les verres de spin reentrants - Isabelle Mirebeau, LaboratoireLéon Brillouin

10:20 - 10:35 › Double vibronic process in the quantum spin ice candidate Tb2Ti2O7 revealed byterahertz spectroscopy - Sophie DE BRION, Institut Néel

10:35 - 11:00 Pause café 11:00 - 12:20 Magnétisme II - Chairman : G. Chaboussant

11:00 - 11:25› Focus - Highly Efficient and Tuneable Spin-to-Charge Conversion at LaAlO3/SrTiO3 Interfaces Through the Inverse Rashba-Edlestein Effect - Manuel Bibes, Unité mixte de physique CNRS/Thales

11:25 - 11:40 › Fragmentation de spins par un champ magnétique alterné dans le composé Ho2Ir2O7 -Julien ROBERT, Institut Néel

11:40 - 11:55 › Comportements de "chaîne-aimant" et "molécule-aimant" dans des oxydes à chaînes despins - Vincent Hardy, CRISMAT

11:55 - 12:10› NMR investigation of the putative Bose-glass regime in the doped DTN at high magnetic fields unveils the existence of a new, impurity-induced BEC-type phase - Mladen Horvatic, Laboratoire national des champs magnétiques intenses

12:10 - 12:20 › Doped DTN at high fields – Theoretical surprise - Nicolas Laflorencie, Laboratoire dePhysique Théorique - IRSAMC

12:25 - 14:00 Déjeuner 14:00 - 15:10 Supraconductivité II - Chairwoman: C. Pépin

14:00 - 14:25 › Focus - Evidences of orbital-selective correlations in the measured gap structure in FeSe- Luca de' Medici, Ecole de Physique et Chimie Industrielle de la Ville de Paris

14:25 - 14:40 › Superconductivity in the iron-based hydride LaFeSiH - Sophie Tencé, CNRS, Universitéde Bordeaux, ICMCB

14:40 - 14:55› Détermination du paramètre d'ordre supraconducteur de FeSe à partir de mesures thermodynamiques, magnétiques et spectroscopiques couplées - Hervé Cercellier, InstitutNéel - Pierre Rodière, Institut Néel

14:55 - 15:10 › Tuning of the phase diagram and quantum critical point by disordered in Fe-basedsuperconductors - Marcin Konczykowski, Laboratoire des Solides Irradiés

15:10 - 15:30 Pause 15:30 - 16:30 Supraconductivité II - Chairman: A. Buzdin

15:30 - 15:45› Stick-slip Phenomena and Memory Effects in Moving Vortex Matter - Lise Serrier-Garcia Brinon, INPAC – Institute for Nanoscale Physics and Chemistry, KU Leuven, LPS– Laboratoire de Physique des Solides

15:45 - 16:00 › Two-dimensional topological superconductivity in Pb/Co/Si(111) - Christophe Brun,Institut des Nanosciences de Paris

16:00 - 16:15 › Electrostatic modulation of superconductivity in few nm BSCCO-2212 films - edoardosterpetti, Institut de minéralogie, de physique des matériaux et de cosmochimie

16:15 - 16:30› Quantum criticality, superconductivity and Fermi surface dimensionality - comparisonof CeIn3, CeRhIn5, and CePt2In7 - Ilya Sheikin, Laboratoire national des champs magnétiques intenses - Grenoble

16:30 - 17:00 Vulgarisation - Chairman: Y. Dumont

16:30 - 17:00 › Vulgariser la matière condensée : pourquoi ? comment ? - Julien Bobroff, Laboratoirede Physique des Solides, CNRS, Univ. Paris-Sud, Université Paris-Saclay

17:00 - 18:30 Sessions parallèles : Poster, Atelier vulgarisation, Visite Aérocampus

vendredi 31 mars 2017

08:45 - 10:20 Phénomènes emergents, corrélations, et dynamique - Chairman: N. Laflorencie

08:45 - 09:25 › Colloque - Kondo effect: an old problem, some new aspects - Claudine Lacroix, InstitutNEEL, CNRS et Université Grenoble Alpes

09:25 - 09:50 › Focus - Electric field induced Insulator to Metal Transition in Mott insulators - BenoitCorraze, Institut des matériaux Jean Rouxel

09:50 - 10:05 › Transition Isolant de Mott-Métal dans Sr2IrO4 - Alex Louat, Laboratoire de Physique desSolides

10:05 - 10:20 › Probing the metal-insulator transition of BaCo1-xNixS2 by optical conductivity - David Santos-Cottin, Laboratoire de Physique et d'Etude des Matériaux, Université Pierre et Marie Curie - Paris 6

10:20 - 10:45 Pause café 10:45 - 12:00 Phénomènes emergents, corrélations, et dynamique - Chairman: V. Ta Phuoc

10:45 - 11:00 › Transition isolant métal induite par pression dans l'isolant de Mott moléculaire organique [Au(Et-thiazdt)2]. - Benjamin Brière, Groupe de Recherche en Matériaux, Microélectronique, Acoustique et NanotechnologiesGREMAN - UMR 7347

11:00 - 11:15 › Instabilités structurales et électroniques des bronzes phosphates de tungstène - AlainPautrat, Laboratoire de cristallographie et sciences des matériaux

11:15 - 11:30 › Determination of the magnetic structure of CePt2In7 by means of neutron diffraction - Matthias Raba, Laboratoire national des champs magnétiques intenses - Grenoble, Institut NEEL, CNRS, University of Grenoble Alpes

11:30 - 11:45 › Neutron diffraction study of CeRh2Si2 under pulsed magnetic field - Naveen Kumar Chogondahalli Muniraju, Laboratoire national des champs magnétiques intenses - Toulouse

11:45 - 12:00 › Electron-phonon coupling in a molecular crystal κ-(BEDT-TTF)2Cu2(CN)3 measured by Resonant Inelastic X-ray Scattering - Vita Ilakovac, Laboratoire de Chimie Physique Matière et Rayonnement

Supraconductivité I

1

Emerging symmetries and the pseudo-gap state of the cuprates

C. Pépin, Institut de Physique Théorique, CEA-Saclay, 91191 Gif-sur-Yvette, France

In this talk we review the state of the art theories and experiments for the longstanding issue of

understanding the pseudo-gap state of the cuprate superconductors. We discuss in particular recent

experiments showing the ubiquitous presence of charge modulations in the under-doped region of this

compounds. A theory where d-wave superconductivity and charge order are connected by an emerging

SU(2) symmetry is then presented and we will focus on its implications for the pseudo-gap line and

the generic phase diagram of these compounds.

meeticc2017 - - Mardi 28 mars 2017 - 14:30/15:10 (40min)

2 sciencesconf.org:meeticc2017:144654

Evidence for hidden fermions and unconventional

pairing in high-temperature superconducting cuprates

Marcello Civelli1

1Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université

Paris-Saclay, 91405 Orsay Cedex, France

Exploiting cluster dynamical mean field theory results on the two

dimensional Hubbard Model, we show that “hidden fermionic

excitations” emerge from the strong electronic correlation. This is a salient

ingredient characterizing cuprate superconductivity. Hidden fermionic

excitations are already present above the superconducting critical

temperature Tc, where they originates the pseudogap, and smoothly

evolve under Tc, giving rise to unconventional pairing mechanism. In

particular, we find that the pairing involves electronic states situated at

energies higher than the superconducting gap energy (and of the order of

the pseudogap energy scale). These phenomena have direct fingerprint in

the Raman B1g response, which displays a characteristic peak-dip feature,

which shows a peculiar behavior across Tc, in good agreement with our

theory. These results reveal an unprecedented relationship between the

pseudogap and superconducting gap, which are at the same time friend and

foes.



High temperature superconducting oxychlorides:a light element model for cuprates.

Blair Lebert1,2, Matteo d’Astuto1, Masaki Azuma3, Ikuya Yamada4

1IMPMC, UMR7590 UPMC-Sorbonne Universites - CNRS, Paris, France

2Synchrotron SOLEIL, Gif-sur-Yvette, France

3Materials and Structures Laboratory, TITech, Yokohama, Japan

4Nanoscience and Nanotechnology Research Center (N2RC), Osaka, Japan

The copper oxychloride cuprate Ca2CuO2Cl2 (CCOC) system, with vacancyor Na doping on the Ca site, is unique among the high temperature supercon-ducting cuprates (HTSCs) since it: lacks high Z atoms; has a simple I4/mmm1-layer structure, typical of 214 (LSCO) cuprates, but which is stable at all dop-ing and temperatures; and has a strong 2D character due to the replacement ofapical oxygen with chlorine [1]. It also shows a remarkable phase digram, witha superconducting TC growing to the optimal doping without any minimumaround 1/8 doping, despite the observation of stripes (or CDW) by near-fieldspectro-microscopy [2].

Due to the reduced number of electrons, advanced calculations that incorporatecorrelation effects, such as quantum Monte Carlo [3], are now feasible for thefirst time in the HTSCs. This makes CCOC a model system to gain insightinto the 30-year-old mystery of HTSCs by bridging the gap between theory andexperiment. But relatively little is known about CCOC (for a cuprate) from anexperimental point of view.

We are now filling this gap by a comprehensive experimental study covering thewhole phase diagram, in particular to the (para)magnon dispersion [4], usingrecent development in RIXS [5], as well as to the phonon dispersion [6]. We arealso looking for a bulk signature of the charge modulation (stripes) from X-rayresonant scattering close to the 1/8 doping.

[1] Z. Hiroi, N. Kobayashi, M. Takano, Nature 371, 139 (1994); Y. Kohsaka et al. JACS 124,12275 (2002); [2] T. Hanaguri et al. Nature 430, 1001 (2004); K. Fujita et al. PNAS 111,E3026-E3032 (2014); [3] K. Foyevtsova et al., Phys. Rev. X 4, 031003 (2014); L. K. Wagner,Phys. Rev. B 92, 161116(R) (2015); [4] B. Lebert et al., arXiv:1610.08383 / hal-01388544; B.Lebert et al., ESRF experiment HC-2702 (2016), article in preparation; [5] M. P. M. Dean,Journal of Magnetism and Magnetic Materials 15, 3 (2015); [6] M. d’Astuto et al. PRB 88,014522 (2013); B. Lebert et al., article in preparation (2017).



(top left) Tetragonal crystal structure of Ca2CuO2Cl2. The square coordination of copperwith its four nearest-neighbor oxygen ions in the CuO2 planes is shown. The chlorine ionsare located in the apical site above and below the copper. Black arrows indicate one of thepossible magnetic structures. (bottom right) Temperature dependence of the fitted intensityof the averaged Bragg reflections ( 1

2, 12, 52

) and ( 12, 12, 72

) and a power law fit (red). From Ref.[4].

X(1/2,0) Γ(0,0) (1/4,1/4) M(1/2,1/2)

q (2π/a)

0

50

100

150

200

250

300

Energ

y (

meV

)

M

XΓ

Dispersion of Ca2CuO2Cl2 measured using Cu L3 RIXS. The red, continuous line is a cal-culation for a classical spin-1/2 2D Heisenberg model with nearest-neighbor exchange andthe blue, dashed line is a calculation including further exchange terms which is described inthe text. (inset) 2D Brillouin zone showing high-symmetry points. The first Brillouin zoneboundary is represented by a thick black square, while the magnetic Brillouin zone boundaryis represented by a dashed line. The region where we measured is shown as two thick red linesalong Γ-X and Γ-M. From Ref. [4].



Evolution of spectral functions and transportquantities with doping in the SU(2) theory of

cuprates.

Corentin Morice1, Catherine Pepin1

1Institut de physique theorique, CEA, Saclay, France

Recent transport experiments in the cuprate superconductors shed new lighton the connection between the enigmatic pseudogap phase and the evolutionof the electronic dispersion under doping. The latter is known to evolve fromFermi arcs measured by ARPES in the underdoped regime, to a large holeFermi surface at high doping, as seen e.g. in quantum oscillation measurements.Combined Hall number and resistivity measurements at high magnetic fieldshowed that the carrier density sharply changes from p to 1+p at the pseudogapcritical doping p∗, linking the opening of the pseudogap to a change in electronicdispersion.

The SU(2) theory of cuprates shows that antiferromagnetic short range inter-actions cause the arising of both charge and superconducting orders, which arerelated by an SU(2) symmetry. The fluctuations associated with this symme-try form a pseudogap phase, which was shown to account for Raman, ARPESand strange metal experimental evidence. Here we derive the renormalised elec-tronic propagator under the SU(2) dome, and calculate the spectral functionsand transport quantities of the renormalised bands. We show that their evolu-tion with doping matches both spectral and transport measurements.



Fermi surface instabilities in ferromagnetic superconductors

Alexandre Pourret1,2, A. Gourgout 1,2, G. Bastien1,2, .G. Knebel1,2, Dai Aoki1,2,3 andJacques Flouquet1,2

1University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France2CEA, INAC-PHELIQS, F-38000 Grenoble, France

3IMR, Tohoku University, Oarai, Ibaraki 311-1313, Japan

In highly correlated electron systems where the relevant energy scales are considerably reduced due to the strong correlations of the partially filled f shells, the ground state is easily tunable under the influence of an external parameter such as pressure or magnetic field. One of the main issue is to understand the interplay of Fermi surface instabilities, magnetic fluctuations and quantum criticality through the competing orders which appears in these systems. Among them, two compounds are particularly interesting, UCoGe and URhGe, because they show the coexistence of two “antagonist” states of matter, ferromagnetism and superconductivity. The most fascinating aspect in UCoGe is the peculiar dependence of the critical field called “S-shape”, for URhGe, it is the apparition of a new superconducting phase under magnetic field (around 12T). Recently, we put emphasis on the important role of Fermi surface on the transport properties in these systems. Indeed, in UCoGe, several successive anomalies were observed under magnetic field (along the easy magnetization c-axis) in resistivity, Hall effect and thermoelectric power, without any thermodynamic transition. The direct observation of quantum oscillations showed that these anomalies are related to topological changes of the Fermi surface, also known as Lifshitz transitions [1]. In URhGe with the field applied along the hard magnetization b-axis, a drastic change in the Fermi surface at the spin reorientation field (HR = 11.75 T) has been observed through thermoelectric power measurements [2]. Additionally, this study allows us to confirm the first order character of the transition and to locate precisely the tricritical point in this compound. This work appears as a pioneering work to understand the effect of magnetic polarization on the Fermi surface topology in highly correlated electronsystems.

[1] G. Bastien, A. Gourgout, D. Aoki, A. Pourret et al., "Lifshitz Transitions in the Ferromagnetic Superconductor UCoGe ", Phys. Rev. Lett. 117, 206401 (2016)

[2] A. Gourgout, A. Pourret, et al., "Collapse of Ferromagnetism and Fermi Surface Instability near Reentrant Superconductivity of URhGe", Phys. Rev. Lett. 117, 046401(2016)



Les cuprates à haute Tc, voix de chimistes

Michel Pouchard1

1 CNRS, ICMCB, UPR 9048, F-33600 Pessac, France

Comment passer de l’isolant de transfert de charge La2CuO4 au liquide de Fermi

LaSrCuO4 ? Une approche basée sur la liaison chimique, ionicité, covalence, transfert

de charge, dipoles de Van der Waals…menée conjointement à une approche physique,

transition de Mott, de Mott-Hubbard, ordre de charge, phonons, polarisation

électronique…sera présentée.

On s’efforcera de rendre compte de l’état de l’art du diagramme de phases en examinant

successivement l’ordre magnétique, son couplage avec le transfert de charge, la

compétition 1D (nématicité)/2D grâce aux interactions entre oxygènes (to-o), enfin la

séparation des sites du cuivre en deux sous réseaux inéquivalents du fait de la symétrie

de translation du vecteur k (ordre orbitalaire ou ordre de liaison). On proposera sur ces

bases une justification de l’existence de deux dômes dans le diagramme de phases.



Nouveaux matériaux

9

Stabilizing several anions (F, O, OH, S) in the vicinity of transition metals or rare

earths to tune the optoelectronic properties of new materials

Alain Demourgues

1CNRS, Université de Bordeaux, ICMCB, 87 Av du Dr A. Schweitzer. 33608 Pessac Cedex. France

Numerous complex oxides exhibiting mixed valence states of 3d-transition metals from insulating to

metallic behaviours have been deeply investigated. For many years, the stabilization of these new

oxides contributes to a better understanding of the relationships between the composition, the

structural features and the electronic properties. The occurrence in the vicinity of transition metals (3d

shell) or rare earth ions (4f and 5d shells) of more than two anions (p shell) with various polarizabilities

leads to an alteration of the energetic parameters such as the crystal-field, the polarizing effects

leading to affect the bandwidth and the position of p and 3d/5d bands, as well as the position of 4f

level in the band gap.

New rare earth Ln-based oxysulfides, fluorosulfides and oxyfluorosulfides have been widely

investigated and exhibit interesting optical properties such as luminescence in Ln2O2S network or

absorption in the visible range in Ln10S14O or LnSF1. Rare earth-based mixed anions (O, S, F)

compounds have been investigated for the last decades2 in order to tune the environment of rare

earth, than modifying optical absorption properties. Most of rare-earth based mixed anions compounds

exhibit 2D-networks due to the presence of anions with various polarizabilities. The building principle

of ionic and covalent sheets in these layered structures with the modification of the block size and

charge based on competitive bonds around the rare earth will be presented. Finally most of these

networks are structurally related to the new generation of superconducting oxypnictides LnMPO1-xFx

(M = Fe, Co, Ni as transition metals and P = P, As, Sb as pnictides) and correspond also to the

succession of ionic (O,F) blocks surrounding rare earth and covalent sheets containing transition

metal3,4

.

New synthesis routes have been developed to stabilize mixed anions compounds. Then new

oxy(hydroxy)fluorides (O/OH/F) with 3D networks have been also obtained and characterized. In

addition, anionic and cationic vacancies have been stabilized in these new compounds prepared by

hydro-solvothermal routes. Relevant examples will be given in the case of Ce4+

(anionic vacancies in

Fluorite-type network) and Ti4+

/Fe3+

(cationic vacancies in ReO3 and HTB frameworks) where the

nature and concentration of anions strongly affect the structural features and the band gap4,5,6

.

References

[1] D. Pauwels, A. Demourgues, H. Laronze, P. Gravereau, F. Guillen, O. Isnard, A Tressaud. SolidState Sciences, 4 (2002) 1471-1479

[2] D. Pauwels, F. Weill, A. Tressaud, A. Demourgues. Chem. Mater, 18 (2006), 6121-6131

[3] B.I. Zimmer, W. Jeitschko, J.H. Albering, R. Glaum, M. J.Reehuis. J Alloys and Comp, 229 (1995),238

[4] Y. Kamihara, H. Hiramatsu, M. Hirano, R. Kawamura, H. Yanagi, T. Kamiya, H. Hosono, J. Am.Chem. Soc, 128 (2006) 10012-10013

[5] A. Demourgues, N. Penin, F. Weill, D. Dambournet, N. Viadere and A. Tressaud. Chem. Mater. 21,

(2009) 1275-1283

[6] Duttine. M, Dambournet. D, Penin. N, Carlier. D, Bourgeaois. L, Wattiaux. A, Chapman. K. W,Chupas. P. J, Groult. H, Durand. E, Demourgues. A. Chem. Mater, 25(14) (2014) 4190-4199

[7] L. Sronek, J. Majimel, Y. Kihn, Y. Montardi, A. Tressaud, M. Feist, C. Legein, J.Y. Buzaré, M. Body

and A. Demourgues. Chem. Mater, 19,n°21, (2007), 5110-5121



Colloque special Transitions et phasestopologiques

11

Quelques propriétés extraordinaires de la physique à

deux dimensions

Jacques Villain1,2

1Institut Laue Langevin, Grenoble, France 2Académie des Sciences, Paris, France

Certains systèmes bidimensionnels présentent un type d’ordre remarquable dont l’étude

a été récompensée par le prix Nobel de physique de 2016. Le plus simple de ces

systèmes est le ferromagnétique à plan de facile aimantation. Il n’a pas d’ordre à grande

distance à température non nulle, mais présente à basse température des corrélations

d’aimantation à décroissance algébrique, comme une puissance r–

de la distance r. La

transition au paramagnétisme correspond à l’apparition de singularités topologiques

appelées vortex, qui deviennent libres alors qu’à basse température elles forment des

paires liées. Cette transition a des propriétés extraordinaires : la chaleur spécifique C et

toutes ses dérivées dnC/dT

n sont des fonctions continues de la température T, mais il

existe une quantité, le coefficient de rigidité, qui a une discontinuité. La meilleure

confirmation expérimentale de la théorie concerne un système différent mais analogue :

le film d’hélium superfluide. La quantité discontinue est alors la densité de superfluide.

Le solide bidimensionnel a lui aussi une phase de basse température sans ordre à longue

distance, mais avec des corrélations de position à décroissance algébrique. Cela veut

dire que les pics de diffraction (dans la limite du système infini) ne sont pas des

fonctions delta comme à 3 dimensions, mais des singularités algébriques. La transition à

la phase liquide peut se faire par une succession de deux transitions continues. La phase

intermédiaire, appelée hexatique, est caractérisée par la présence de dislocations libres.

Elle présente des corrélations orientationnelles qui décroissent algébriquement avec la

distance. La formation de la phase liquide est due à un autre type de singularité

topologique : les disclinaisons.

meeticc2017 - - Mercredi 29 mars 2017 - 8:45/9:25 (40min)


Magnétisme I

13

Frustration, chirality, multiferroism

Virginie Simonet Institut Néel, CNRS and University Grenoble Alpes, 38042 Grenoble, France,

[email protected]

In this talk, I will recall some basic concepts of magnetic frustration that can lead to

unconventional behaviours and phases such as spin liquid, spin ices but also complex

magnetic orders. These, associated to charge and lattice degrees of freedom, can lead to

multiferroism, that is to say the coexistence of at least two ferroic orders in the same

material. Important issues in this field are the magnetoelectric effect, the manipulation of

magnetic/ferroelectric domains, and the chirality. Some emphasis will be given to this

latter fruitful concept, which characterises important magnetic materials beyond the class

of multiferroics.



Interplay between charge transfer and magnetic

transition in the quadruple perovskite (YMn3)Mn4O12

Marine Verseils1, Francesco Mezzadri

2, Davide Delmonte

2, Benoit Baptiste

1, Yannick

Klein1, Laurent Chapon

3*, Edmondo Gilioli

2 and Andrea Gauzzi

1

1IMPMC-UMR 7590, UPMC, Paris, France

2IMEM-CNR, Parma, Italy

3ILL, Grenoble, France (* Present address: Diamond, Oxford, UK)

The quadruple perovskitesystemAMn3Mn4O12(QP-Mn) (A=Na, Ca, La, Bi), has

attracted a great deal of interest because of theunique charge, spin and orbital orderings

arising from two distinct magnetic A’- and B-sublattices and from the absence of

oxygen defects. Most notable are a full charge order [1, 2] and multiferroicity

[3,4,5,6].The stability conditions of these orderings depend on two distinct B-O-B and

A’-O-B superexchange paths, characterized by an unusuallylarge tilt of the BO6

octahedra with Mn-O-Mn bondangles ~136°, thusleading to competing AFM or FM

exchange interactions not explained by the GKA rules.

In order to investigate the role of the bond geometry on the stability of competing

magnetic structures in the system, we have successfully synthesized under high pressure

and studied the structural and magnetic properties of (YMn3)Mn4O12, where the small

Y3+

ion is expected to enhance the magnetic exchange interaction with respect to the

isovalent compound (LaMn3)Mn4O12. According to this expectation, we have observed

the highest AFM ordering temperature for the B-sites, TN,B=108K. On the other hand,

we have found four unexpected features, not reported before in other AMn3Mn4O12

compounds:(1) a second-order structural phase transition at 200 K that seems to be a

precursor of the AFM ordering of the B-sites at low temperature; (2) the absence of any

magnetic ordering of the A’ sublattice, which has systematically been found in other

AMn3Mn4O12 compounds in the 20-60 K range; (3) on the other hand, susceptibility

measurements at low field unveil an anomaly suggesting the existence of a latent

ordering; (4) at low-temperature the specific heat follows an unusual quadratic - instead

of cubic - dependence, which suggests that excitations other than acoustic phonons

dominate the entropy.

The above anomalies call for further studies, e.g. RIXS, that may probe the electronic

excitation spectrum, possibly dominated by the proximity of competing magnetic

orderings.

References:

[1]A. Prodi et al., Nature materials, 3, 48-52 (2004)[4] R.D Johnson et al., Physical Letters B, 108, 6 (2012)

[2] A. Prodi et al., Physical review B, 90, 180101 (2014) [5] X.Z. Lu et al.,Physical review Letters, 108, 18 (2012)

[3] G.Zhang et al., Physical review B, 84, 17 (2011)[6] F. Mezzadri et al., Physical review B, 79, 10 (2009)



Field-induced quasiparticles driving the quantum phase

transition in Ising-like antiferromagnetic spin chain

Quentin Faure1,2, Virginie Simonet2, Sylvain Petit3, Louis-Pierre Regnault1, Martin

Boehm4, Stéphane Raymond1, Jonathan White5, Martin Månsson6, Christian Rüegg5,

Benjamin Canals2, Shintaro Takayoshi7, Shunsuke Furuya7, Thierry Giamarchi7, Claude

Berthier8, Pascal Lejay2, Béatrice Grenier11 INAC, MEM, CEA–UGA, Grenoble, France

2 Institut Néel, CNRS–UGA, Grenoble

3 IRAMIS, LLB, CEA–CNRS, Gif-sur-Yvette, France

4 ILL, Grenoble, France

5 PSI, Villigen, Switzerland

6 KTH Royal Institute of Technology, Stockholm, Sweden

7 DPMC-MaNEP, University of Geneva, Switzerland

8LNCMI, CNRS–UGA–UPS–INSA, Grenoble, France.

BaCo2V2O8 is a realization of a spin-1/2 Ising-like quasi-one dimensional

antiferromagnet with remarkable static and dynamical behaviors [1]. In zero-field, the

excitations of the Néel phase consist in confined two-spinon excitations stabilized by

weak interchain interactions. They actually form two interlaced long-lived Zeeman

ladders with respective transverse (T) and longitudinal (L) character regarding the

direction of the magnetic moments (along the chain 𝑐-axis) [2]. We have explored the

influence of an external magnetic field on this spin dynamics by inelastic neutron

scattering on TASP (PSI) and on ThALES and IN12 (ILL) [3]. A contrasting behavior

is observed for a longitudinal and transverse magnetic field. In the former case, the Néel

phase excitations keep their transverse or longitudinal character, simply showing a

Zeeman behavior up to the critical field at which the Néel ordering turns into a

longitudinal spin density wave. The more spectacular effect comes with the transverse

field where a mixing of the excitations occurs, hence materializing new kinds of

entangled quasiparticles with both L and T characters. The lowest energy mode

transforms progressively from transverse to longitudinal, before collapsing at the critical

field marking a quantum phase transition to a novel phase [3].

References [1] S. Kimura et al., PRL 99, 087602 (2007); [2] B. Grenier et al.,, PRL 114, 017201 (2015); ibid., PRL 115, 119902 (2015);[3] Q. Faure et al., in preparation.



Deux articles intéressants

Mario Maglione, ICMCB-CNRS-Univ.Bordeaux

Ferroelectric or non-ferroelectric: why so many materials exhibit “ferroelectricity” on the nanoscale

Rama K. Vasudevan, Nina Balke, Peter Maksymovych, Stephen Jesse and Sergei V. Kalinin

arXiv:1701.01128

Strain-Induced Ferroelectric Topological Insulator Shi Liu, Youngkuk Kim, Liang Z. Tan, and Andrew M.

Rappe Nanoletters 2016, 16, 1663−1668

[email protected]



Pressure induced multiferrocity in PrMn2O5

W. Peng, V. Balédent, S. Chattopadhyay, M.-B. Lepetit, G. Yahia, C. V. Colin, M. Greenblatt,

and P. Foury-Leylekian

Multiferroics which exhibit coupled electric polarization and magnetization, are

exceptional multifunctional materials. They can respond to the application of both electric

and magnetic fields, and thus can allow a much greater degree of control for electronic device.

The RMn2O5 series of multiferroic is extensively studied for its strong magneto-electric

coupling (MEC). The microscopic mechanism of the MEC has been nearly clarified and is

associated with the exchange-striction model. Since small variations of the interatomic

distances directly modify the superexchange integrals, one can expect the multiferroic

properties to be strongly affected by the external pressure. In contrast with the other members

of the RMn2O5 family, PrMn2O5 is paraelectric at ambient pressure. This makes it the best

candidate for a pressure induced multiferroicity, never encountered before.

We report here the first accurate determination of the magnetic structure under pressure in

the PrMn2O5 by powder neutron diffraction. A new magnetic phase is revealed. It presents at

low pressure (2 GPa) and becomes completely exclusive at 8 GPa. This pressure induced

phase seems to have a universal character because it has been observed already in YMn2O5.

In PrMn2O5, the magnetic direction developing under pressure has a new behaviour. While

the spins are perpendicular to each other at ambient pressure in PrMn2O5, leading to the

absence of electric polarization. The spins become collinear under pressure, which is exactly

what expected within the framework of the exchange- striction model.

This presages a pressure induced multiferroic transition in the non-ferroelectric PrMn2O5 and

paves the way to the conception of new multiferroic materials with tunable properties.



Chiral spin liquid on kagome antiferromagnetinduced by Dzyaloshinskii-Moriya interaction

Laura Messio1, Samuel Bieri2, Claire Lhuillier1, Bernard Bernu1

1Laboratoire de Physique Theorique de la Matiere Condensee, CNRS UMR7600, Universite Pierre et Marie Curie, Sorbonne Universites, 75252 Paris,

France

2Institute for Theoretical Physics, ETH Zurich, 8099 Zurich, Switzerland

Herbertsmithite was the first perfect kagome compound, realised in 2005, lead-ing to the first observation of a spin liquid. But the precise nature of thisphase remains controversial as different spin liquids, characterized by unusualquantum number (symmetry fractionnalisation quantum numbers) exist. Sincethen, crystal synthesis revealed a quasi dispersionless low energy structure factor(Han et al, Nature 2012). This kagome antiferromagnet is notably perturbed bya small Dzyaloshinskii-Moriya interaction (DMI). We analyze the expression ofthis interaction and show that DMI reduces frustration on the kagome lattice.Schwinger boson mean-field theory (SBMFT) has recently been largely usedcombined with the projective symmetry group approach. Thus, only Ansaetzeconstrained to respect the lattice symmetries are considered. We use it herewith the DMI, considering also time reversal symmetry breaking states andfind a new chiral spin liquid having interesting low energy properties (Arxiv1701.01243), comparable to the experimental results. We detail the specifici-ties of this phase with respect to the previously proposed ones and present thetheoretical phase diagram and dynamical structure factor calculations.

AB SBMFT

A1(0, 0, 1)

q = 0 (LRO)

A4(1, 1)

A1(1, 0, 1)

A4(0, 1)

0

0.1

0.2

0.3

S

0 0.1 0.2 0.3θ

Phase diagram obtained with SBMFT. The new chiral phase is the yellow one.



Emergent phenomena in spin liquids

Ludovic Jaubert1,2, Marion Brooks-Barklett3, Simon Banks3, Adam Harman-Clarke3,4, Peter Holdsworth4, Taoran Lin5, Tuba Opel5, Michel Gingras5,6,7, Claudio Castelnovo8, Roderich Moessner9, Tomonari Mizoguchi10, Masafumi Udagawa11, Owen Benton12,

Han Yan2, Nic Shannon2

1LOMA, University of Bordeaux, France 7CIFAR, Toronto, Canada2OIST, Okinawa, Japan 8University of Cambridge, UK

3University College London, UK 9MPI-PkS, Dresden, Germany4ENS Lyon, France 10University of Tokyo, Japan

5University of Waterloo, Canada 11University of Gakushuin, Tokyo, Japan6Perimeter Institute, Waterloo, Canada 12RIKEN, Tokyo, Japan

Spin liquids are malleable magnetic textures obeying their own microscopic rules. These rules, due to frustrated constraints, can take the form of emergent gauge fields able to support quasi-particles, readily accessible by experimental probes.

In this talk we will illustrate the diversity of emergent phenomena supported by spin liquids, starting from the Coulomb gauge field of spin-ice materials. This Coulomb field can be for example confined in thin-film geometries, or serve as a foundation for exotic phases such as fragmented spin liquids — coexisting with long-range order — whose excitations are reminiscent of the particle-hole physics of semi-conductors. Beyond Coulomb gauge field, we will discuss how topological defects can form fluctuating clusters without long-range order, and how other forms of gauge fields, such as linearised general relativity, can appear in a crystal.

Pinch line singularities: signatures of an emergent gauge field beyond electromagnetism



Techniques avancées

21

Techniques spectroscopiques avancées pour l’étude

des systèmes corrélés

Jean-Pascal Rueff1,2

1Synchrotron SOLEIL, Gif sur Yvette, France

2Laboratoire de Chimie Physique – Matière et Rayonnement, CNRS UPMC, Paris

L’émergence de sources X de haute brillance a rendu possible le développement de

nouvelles techniques de spectroscopie qui nécessitent à la fois un important flux de

photons, une forte focalisation et une haute résolution. C’est le cas de la diffusion

inélastique des rayons X (RIXS) et de la photoémission de haute énergie cinétique

(HAXPES) qui seront discutées ici. Nous verrons à travers des résultats récents les

apports de ces techniques pour l’étude des systèmes d’électrons fortement corrélés et

matériaux émergents, notamment dans les oxydes, les supraconducteurs sous conditions

extrême et les matériaux 2D. Nous discuterons des perspectives dans ce domaine.



Sonder et impacter les matériaux aux échelles de temps

ultra-rapides

Eric Collet1

1Univ Rennes 1, CNRS, UBL, Institut de Physique de Rennes, UMR 6251, F-35042

Rennes, France

Le développement d'impulsions ultra-brèves dans une large gamme spectrale (THz, IR,

VIS, UV, X…), atteignant le domaine femtoseconde (10-15

s) voire attoseconde (10-18

s),

permet d'explorer de nouveaux domaines de la physique [1-6]. Elles génèrent de

nouveaux états de la matière tels que plasmas, matière dense et chaude fortement

corrélée, états fortement ionisés. Elles transforment aussi des molécules ou des

matériaux de façon ultra-rapide. La lumière peut ainsi générer la fusion non thermique

d'un cristal, exciter de façon cohérente un ou plusieurs phonons, contrôler le

magnétisme (jusqu'à l'échelle nanométrique) ou la piézoélectricité, ou encore piloter de

véritables transitions de phases photo-induites entre états isolant et métallique, para- et

ferro-électrique, dia- et para-magnétiques via une excitation électronique ou encore une

onde de choc. Le développement d'expériences pompe-sonde permet d'étudier en temps

réel la dynamique de la matière, en particulier dans des états fortement hors équilibre.

Les sondes sensibles aux degrés de libertés électroniques, structuraux ou vibrationnels

révèlent ainsi comment ils évoluent sur leurs propres échelles de temps et d'espace mais

aussi comment ils se couplent entre eux. Mais ces impulsions laser ultra-brèves

permettent aussi d'impacter la matière en jouant sur l'énergie d'excitation, les champs

électrique ou magnétique ou le nombre de photons excitant la matière.

Activation d'un phonon

cohérent du Bismuth par

impulsion laser, observée

par diffraction X

femtoseconde.

[E. Collet et al, Reflet de la

physique, numéro spécial

cristallographie (2015)]

[1] P. Babilotte, et al, Appl. Phys. Lett., 97, 174103 (2010)

[2] H. Baida, Phys. Rev. Lett. 107, 057402 (2011)

[3] H. Vincenti et al, Phys. Rev. Lett. 108 (2012) 113904

[4] J.Y. Bigot Nature Materials 12, 283–284 (2013)

[5] S. Corde et al, Rev. Mod. Phys. 85, 1-48 (2013)

[6] R. Bertoni et al, Nature materials 15, 606-610 (2016)



Time-resolved X-ray Diffraction on Density-Waves systems

Sylvain Ravy1, Claire Laulhé

2, Tim Huber

3, A Ferrer

4, Gabriel Lantz

1, Vincent Jacques

1,

David Le Bolloc'h1, S.O. Mariager

4, L. Cario

5, B. Corraze

5, E. Janod

5, Gerhard Ingold

4, Paul

Beaud4, S.L. Johnson

3

1 Laboratoire de Physique des Solides, Orsay, France,

2 Synchrotron-SOLEIL, Gif-sur-Yvette, France,

3 Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland,

4 Swiss Light Source, Villingen, Switzerland E-mail: [email protected]

5 Institut des Matériaux Jean Rouxel, F-44322 Nantes, France

Spin- (SDW) and Charge-density waves (CDW) systems are ubiquitous states in solid state

physics. They both correspond to a modulation of the spin- or the charge-density, with twice

the Fermi wave vector of the electron gas. Both states are gapped, which make them sensitive

to impulsive absorption of laser infrared pulses. Interestingly enough, CDW are generally

coupled to the lattice, which make them easy to observe by X-ray diffraction.

In this work, we compare the dynamical behavior of CDW after an infrared laser pulse in

three different DW systems: Chromium [1], K0.3MoO3 (so-called blue bronze) [2], and 1T-

TaS2 [3]. In all three cases, the CDW is strongly depressed after the pulse in an ultrafast way,

which could lead either to a melting of the state, or to a photo-induced phase transition

towards another CDW state. In the 1T-TaS2 case, it has been possible to watch the birth of a

CDW phase with a nucleation-growth-coarsening process [3].

The recovery of the initial CDW state follows different mechanisms which depend on the

compound.

[1] V.L.R. Jacques et al., Phys. Rev. Lett. 117, 156401 (2016)

[2] T. Huber et al., Phys. Rev . Lett. 113, 026401 (2014)

[3] C. Laulhé et al., to be published



Collective transport of charges in charge density wave

sytem based on traveling soliton lattices

Ewen Bellec1, Isabel Gonzalez-Vallejo

2, Vincent Jacques

3, David Le Bolloc'h

3

Paris-Sud University1,2

, CNRS3, LOA

2, Orsay, France

A charge density wave (CDW) system is a low dimensional crystal (quasi-1D or quasi-

2D) made of spatially correlated electrons. Although the static CDW state is now well

understood, the dynamical one is still debated. Indeed, the most spectacular property of

a CDW system is its ability to carry correlated charges when submitting the sample to

an external electric field. Above a threshold field Eth, a nonohmic resistivity is observed.

The voltage becomes periodic with a fundamental frequency f 0 proportional to the

applied field as well as several harmonics. This evidence of collective transport through

CDW systems has received considerable interest for more than 35 years. However, the

understanding of the type of charge carriers and their propagation mode remains

incomplete.

Solitons are localized excitations that appear in many theory when dealing with non-

linear interactions, such as in magnetism, optics, fluids mechanics. We show here that

this collective transport of charge in blue bronze K0.3MoO3 can be explained using a

theory of a travelling soliton lattice. Coherent x-ray diffraction experiment performed in

the sliding state of the CDW reveals peculiar diffraction patterns in good agreement

with this assumption [1]. In this semiclassical description, charges are carried by phase

shifts of the CDW modulation which can travel through macroscopic samples without

deformation on top of the CDW ground state. This single theory explains why charges

remain spatially correlated over very long distances and reconciles the main features of

sliding CDW systems, either observed by transport measurements or diffraction.

[1] A. Rojo-Bravo, V. L. R. Jacques, and D. Le Bolloc'h. Collective transport of charges in charge density wave systems based on traveling soliton lattices. Phys. Rev. B,94:201120, Nov 2016. [2] David Le Bolloc'h, Ewen Bellec, Isabel Gonzalez-Vallejo, Vincent Jacques.

Fluctuating soliton lattice. Article in preparation.

Figure 1: Sketch of the static soliton

lattice in real space. (a) CDW in the

presence of a soliton lattice with (b) the

corresponding electronic density profile

and (c) the corresponding phase ϕ1.



Three-dimensional critical phase diagram of a heavy-

fermion Ising antiferromagnet

William Knafo 1, Rikio Settai

2, Daniel Braithwaite

3, Shuhei Kurahashi

4, Dai Aoki

3,5,

and Jacques Flouquet3

1 Laboratoire National des Champs Magnétiques Intenses, UPR 3228, CNRS-UPS-

INSA-UGA, 143 Avenue de Rangueil, 31400 Toulouse, France

2 Department of Physics, Faculty of Science, Niigata University, 8050 Ninocho

Ikarashi, Nishi-ku, Niigata 950-2181, Japan

3 Université Grenoble Alpes and CEA, INAC-PHELIQS, F-38000 Grenoble, France

4 Graduate School of Science and Technology, Niigata University, 8050 Ninocho

Ikarashi, Nishi-ku, Niigata 950-2181, Japan

5 Institute for Materials Research, Tohoku University, Ibaraki 311-1313, Japan

Non-destructive pulsed magnetic fields permit to explore the magnetic phase diagrams

of strongly-correlated electrons systems. After an introduction to the pulsed-field

technique, I will present a recent work performed on a heavy-fermion antiferromagnet.

Novel instrumentation, which allows combining extreme conditions of intense pulsed

magnetic field up to 60T and high pressure up to 4 GPa (developed within a

collaboration between the CEA-Grenoble, the University of Niigata, and the LNCMI-

Toulouse), has been used to establish the three-dimensional (3D) magnetic field -

pressure - temperature phase diagram of the pure stoichiometric antiferromagnet

CeRh2Si2. This phase diagram shows a temperature- and pressure-dependent decoupling

of the critical and pseudo-metamagnetic fields, at the borderlines of antiferromagnetism

and strongly-correlated paramagnetism. It is representative of a class of heavy-fermion

Ising antiferromagnets, where long-range magnetic ordering is decoupled from a

maximum in the magnetic susceptibility.

References:

1. “ Three-dimensional critical phase diagram of the Ising antiferromagnet CeRh2Si2 under

extreme conditions of pressure and magnetic field“, W. Knafo, R. Settai, D. Braithwaite, S.

Kurahashi, D. Aoki, and J. Flouquet, Phys. Rev. B 95, 014411 (2017)

2. “Pressure cell for transport measurements under high pressure and low temperature in

pulsed magnetic fields“, D. Braithwaite, W. Knafo, R. Settai, D. Aoki, S. Kurahashi, and J.

Flouquet, Rev. Sci. Instrum. 87, 023907 (2016).

3. “Development of Bridgman-Type Pressure Cell for Pulsed High Magnetic Field”, R. Settai,

W. Knafo, D. Braithwaite, S. Kurahashi, D. Aoki, and J. Flouquet, Review of High Pressure

Science and Technology / Koatsuryoku No Kagaku To Gijutsu 25, 325 (2015).



Nouveaux matériaux

27

Multiferroics: What now?

Nathalie Viart

Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de

Strasbourg, UMR 7504, F-67000 Strasbourg, France

Multiferroic materials, in which magnetic and electric orders coexist, and

magnetoelectric materials, in which the magnetic and electric properties are coupled,

have been the object of a tremendous scientific excitation in the last ten years for they

theoretically unlock paths towards higher density and lower power consuming data

storage technologies.

If important discoveries have been done concerning the mechanisms underlying these

phenomena, the disappointing amplitude of the observed effects,when compared to what

is desired for actual devices, have put down most of the early days enthusiasm concerning

these materials. The interest has now shifted towards adjacent fields of research

pioneered during the search for enhanced effects. Among the considered issues, one finds

the rich physics offered by the interfaces in heterostructures studied in the first place for

the possibility they offer to better couple electric and magnetic properties.

However the quest for new multiferroics continues with that construction philosophy, but

on much smaller scales, going down to atomic scale tailorization of the materials.

I will present the routes currently considered with both physical and chemical elaboration

tools.



AMnGe2O6 (A = Ca or Sr) : effet de la nature du cation

divalent dans la structure pyroxène

Lei Ding1,2

, Claire V. Colin1,2

, Céline Darie1,2

, J. Robert1,2

, F. Gay1,2

, Pierre Bordet1,2

1 Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble, France

2 CNRS, Inst NEEL, F-38000 Grenoble, France

Les composés de structure pyroxènes de formule chimique AMT2O6 (A = métal

mono- ou divalent, M = métal de transition di- ou trivalent, T = Si or Ge) contenant des

ions magnétiques ont été très étudiés ces dernières années révélant des propriétés

magnétiques originales (quasi-1D) ou encore des propriétés multiferroïques. A ce jour,

assez peu d’études ont exploré les composés divalents, notamment les composés

contenant du strontium.

Dans ce travail nous présentons la synthèse chimique par méthode sur poudre et

monocristal, la résolution de la structure cristallographique et les propriétés

magnétiques et magnéto-électriques de deux composés de la série des pyroxènes :

AMnGe2O6 avec A = Ca, Sr.

Pour le composé au calcium les études par diffraction des neutrons combinées à des

mesures magnétiques revèle la présence de corrélations de spins à courte distance au

dessus de la température de Néel TN=15K et montre un comportement

magnéto-électrique linéaire.

Le comportement du composé au strontium est bien différent. La détermination de la

structure magnétique, jusqu’alors inconnue, montre en effet une structure magnétique

cycloîdale induisant l’existence de multiferroïcité en dessous de 4,5K.

Fig. 1 Vue schématique de la structuremagnétique cycloïdale de SrMnGe2O6 en dessous de TN projetée dans le plan (a, b) (vue de dessus)et le plan (a, c) (vue de dessous)



Rb2Ti2O5: quand un diélectrique n'est pas un isolant...

Rémi Federicci , Stéphane Holé et Brigitte Leridon

LPEM-ESPCI Paris, PSL Research University,

CNRS, Sorbonne Universités, UPMC, 10 rue Vauquelin, 75005 Paris, France

Une conductivité électrique et une constante diélectrique élevées sont en principe

incompatibles, ce qui fait que les termes “isolant” et “diélectrique” sont en général

confondus. Ceci est certainement vrai lorsque les porteurs de charge sont des électrons

mais pas nécessairement dans un matériau où des espèces ioniques sont fortement

mobiles, où la conduction électronique est négligeable et les transferts de charge à

l'interface inexistants. Dans ce cas, bien que le matériau conduise la charge de

manière interne, il peut posséder une polarisation et une constante diélectrique très

élevées.

Nous présenterons les propriétés électriques d'un nouveau titanate bi-dimensionnel:

Rb2Ti2O5. Ce matériau présente des cycles I_V de type ferroélectrique avec une

constante diélectrique colossale à basse fréquence (de l'ordre de 109).

Des investigations détaillées de la constante diélectrique permettent de démontrer qu'en

raison de mouvemenst ioniques, ce matériau se comporte comme une dipôle géant avec

une polarisation de type ferroélectrique colossale (de l'ordre de 0.1 C.cm-2). Ce

matériau, très prometteur pour les applications peut donc être qualifié de

“ferroélectrique ionique” ou encore de “ferro-ionet”.



Toward a gated FET on the basis of spin-transition polymers

S. V. Andreev and S. Burdin University of Bordeaux, LOMA (CNRS)

We present a theoretical model of spin transitions in stacks of molecular layers. Our

model captures the already established physics of these systems (thermal hysteretic

crossovers and transitions) and suggests a way towards in situ control of this physics

by means of external fields applied to the boundary layer. Our results pave the way

toward both temperature and voltage controllable organic memory.



Magnétisme II

32

Frustration, quantum magnetism and spin liquids

Fabrice Bert1

1Laboratoire de Physique des Solides, CNRS,Univ. Paris-Sud, Université Paris-Saclay,

91405 Orsay, France

While spin chains constitute the natural playground for quantum magnetism, extending

this physics to higher dimensions has turned out to be an enduring and rewarding quest

with the discovery of many novel exotic states. One emblematic example is the

antiferromagnetic Heisenberg model for S=1/2 spins on the kagome lattice made of

corner sharing triangles. Despite it seemingly simple nature, this highly frustrated spin

model continues to challenge theory and material science to find good material

realizations. I will discuss recent advances in the field from an experimental perspective.

meeticc2017 - - Jeudi 30 mars 2017 - 9:00/9:40 (40min)


Systèmes artificiels, systèmes modèles

B. Canals

1Université Grenoble Alpes, Institut Néel, F-38000 Grenoble, France

2CNRS, Institut Néel, F-38000 Grenoble, France

Je discuterai quelques résultats récents obtenus dans les systèmes magnétiques artificiels,

systèmes qui se développent depuis une dizaine d’années, avec comme ligne directrice la

réalisation de phases magnétiques originales qui n’ont que peu, voire aucune réalisation

équivalente, en matière condensée: parmi ces états originaux magnétiques, j’aborderai sans

doute les phases de Coulomb, les glaces de spins dipolaires, les cristaux de charges

magnétiques, les quasi-particules typiques comme les monopoles magnétiques classiques, les

phases thermiques, la cinétique de désaimantation.



Défauts topologiques dans les verres de spin reentrants

I. Mirebeau1,*

, N. Martin1, M. Deutsch

2, L. Bannenberg

3, C. Pappas

3, R. Cubitt

4,

A. O. Leonov5

1. Laboratoire Léon Brillouin, Université Paris-Saclay, 91191 Gif-sur-Yvette France

2. Université de Lorraine, CRM2, 74506, Vandoeuvre-les-Nancy, France

3. Faculty of Applied Science, Delft University of Technology, 2629 JB Delft, The Netherlands

4. Institut Laue Langevin, BP156, F-38042 Grenoble France

5. Center for Chiral Science, Hiroshima Univ., Higashi-Hiroshima, 739-8526 Japan

Les verres de spin réentrants présentent des interactions magnétiques en compétition,

avec une dominante ferro- ou antiferromagnétique, associées à un désordre chimique.

La frustration est contrôlée par la concentration magnétique x et le diagramme de phase

(T,x) bien décrit par une théorie de champ moyen. Dans les années 80, les mesures de

diffusion de neutrons aux petits angles (DNPA) ont mis en évidence des structures de

type vortex dans la phase réentrante de ces systèmes sous champ magnétique. Les

composantes transverses au champ tournent sur des échelles de longueur typiques allant

de 1 à 10 nm [1]. Des structures similaires ont aussi été trouvées par simulation Monte

Carlo (MC) à 2 dimensions [2].

Nous avons effectué de nouvelles mesures de DNPA pour étudier les différences entre

ces défauts et les « skyrmions » magnétiques. Dans le composé monocristallin

faiblement frustré Ni0.81Mn0.19 (TC=250K) nous observons un désordre aléatoire (ou un

ordre de type liquide) de ces défauts, dont la taille décroit quand le champ magnétique

augmente en suivant des lois d’échelle, jusqu’à très fort champ. Aucune composante

longitudinale MZ (le long du champ) n’est observée dans la fenêtre de la DNPA, ce qui

signifie que MZ est modulée seulement à l’échelle locale.

Des simulations Monte Carlo récentes, à 2 et 3 dimensions, effectuées pour des spins

Heisenberg couplés ferromagnétiquement avec une faible concentration de liaisons AF,

montrent que: i) comme pour les skyrmions, le cœur du vortex est opposé au champ ; ii)

les défauts se présentent par paires et présentent un mélange de charges topologiques

positives et négatives, indépendamment de la chiralité. Une comparaison qualitative

avec l’expérience suggère de les associer à des paires Mn-Mn premiers voisins

Dans les composés faiblement frustrés, ces résultats montrent qu’on peut piloter

indépendamment les longueurs de cohérence longitudinale et transverse de ces

« skyrmions frustrés », en jouant respectivement avec la concentration magnétique (ou

le traitement thermique) et le champ magnétique. En augmentant la frustration, on peut

aussi suivre leur évolution au voisinage du point critique quantique qui sépare la phase

verre de spin réentrante d’une phase verre de spin classique.

[1] M. Hennion, I. Mirebeau et al, Europhys. Lett 2, 393, (1986).

[2] H. Kawamura and M. Tanemura, J.Phys. Soc. Jpn 60, 1092, (1991).



Double vibronic process in the quantum spin ice candidate Tb2Ti2O7 revealed by terahertz

spectroscopy

S. deBrion, CNRS, Inst Neel, F-38042 Grenoble, France



Highly Efficient and Tuneable Spin-to-Charge Conversion at

LaAlO3/SrTiO3 Interfaces Through the Inverse Rashba-Edlestein Effect

E. Lesne1, Y. Fu

2, S. Oyarzun

2,3, J.C. Rojas-Sanchez

1, D.C. Vaz

1, H. Naganuma

1,4, G. Sicoli

2, J.-P. Attané

2,

M. Jamet2, E. Jacquet

1, J.-M. George

1, A. Barthélémy

1, H. Jaffrès

1, L. Vila

2, A. Fert

1 and M. Bibes

1*

1 Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France

2 INAC/SP2M, CEA-UJF, 38054 Grenoble, France

3 Departamento de Física, Universidad de Santiago de Chile (USACH), Chile

4 Tohoku University, Department of Applied Physics, 6-6-05 Aoba, Aramaki, Aoba, Sendai 980-8579, Japan

* [email protected]

The spin-orbit interaction couples the electrons' motion to their spin. Accordingly, passing a

current in a material with strong spin-orbit coupling generates a transverse spin current (spin

Hall effect, SHE) and vice-versa (inverse spin Hall effect, ISHE). The emergence of SHE and

ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronics

functionalities and devices, some of which do not require any ferromagnetic material.

However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk

property that rarely exceeds ten percent, and does not take advantage of interfacial and

low-dimensional effects otherwise ubiquitous in spintronics hetero- and mesostructures. In

this talk, we will show how to make use of an interface-driven spin-orbit coupling

mechanism the Rashba effect in the oxide two-dimensional electron system (2DES)

LaAlO3/SrTiO3 to achieve spin-to-charge conversion with unprecedented efficiency. Through

spin-pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the

resulting charge current, which can be strongly modulated by a gate voltage. We discuss the

amplitude of the effect and its gate dependence on the basis of the electronic structure of the

2DES.



Fragmentation de spins par un champ magnétique alternédans le composé Ho2Ir2O7

E. Lefrançois1,2, V. Cathelin2, E. Lhotel2, J. Robert2, P. Lejay2, C. V. Colin2, B. Canals2, F.Damay3, J. Ollivier1, B. Fak1, L. C. Chapon1, R. Ballou2, V. Simonet2

1Institut Laue Langevin, CS 20156, 38042 Grenoble, France2Institut Néel, CNRS and Univ. Grenoble Alpes, 38042 Grenoble, France

3Laboratoire Léon Brillouin, CEA, CNRS, Univ. Paris-Saclay , F-91191 Gif-sur-Yvette, France

La frustration magnétique se base sur un concept très simple (compétition entre différentsdegrés de libertés) menant toutefois à une très grande variété d’états magnétiques originaux. Cesétats peuvent aller d’ordres magnétiques complexes à des phases restant quant à elle “désordonnées”jusqu’aux plus basses températures telles que les glaces de spin, dont les excitations élémentaires,tout à fait singulières, peuvent être décrites comme des charges (ou “monopoles magnétiques”)diffusant à travers le réseau. Dans ce domaine, un intérêt tout particulier s’est récemment développépour tenter de comprendre comment cette vision “binaire” (ordre à longue portée vs corrélationsà courte portée) laisse place dans certains systèmes à une situation intermédiaire dans laquellel’ordre et le désordre coexistent, et sont même parfois partagés par un unique degré de liberté.C’est le cas de la fragmentation de spins, phénomène introduit récemment dans le cadre desglaces de spin et depuis observé dans plusieurs systèmes [1].

En confrontant prédictions théoriques et résultats expérimentaux obtenus dans le composépyrochlore Ho2Ir2O7, nous montrons qu’une telle fragmentation des spins peut aussi provenir del’application d’un champ magnétique. Dans le cas présent, ce champ magnétique alterné, créé parles ions d’iridium, est intrinsèque à l’échantillon et déstabilise l’état glace de spin porté par lesions d’holmium. Leurs moments magnétiques se fractionnent alors en deux parties, contribuant àla fois à un ordre de charge induit par le champ, et un état fluctuant non chargé. Nous montronsfinalement que les excitations élémentaires d’une telle phase mixte sont, tout comme dans la glacede spin conventionnelle, des charges, diffusant cette fois-ci dans le potentiel périodique induit parle cristal de charge (voir figure 1) [2].

Figure 1 – Représentation schématique unidimensionnelle de la diffusion d’une charge positive(excitation élémentaire) à travers le crystal de charge. Dans ce dernier, les tétraèdres formés parles ions d’holmium (brique élémentaire du réseau pyrochlore) sont représentés en gris et portentune charge statique positive (rouge) ou négative (bleu).

[1] M. E. Brooks-Bartlett et al., Phys. Rev. X 4, 011007 (2014) ; S. Petit et al., Nature Physics12, 746-750 (2016) ; B. Canals et al., Nature Communications 7, 11446 (2016). [2] E. Lefrançois etal., arXiv1702.02864 (2017).



Comportements de chaîne-aimant et molécule-aimant dans des oxydes à chaînes de spins

Vincent Hardy1, Motin Seikh2, Vincent Caignaert1, Olivier Perez1, et Bernard Raveau1

1 Laboratoire CRISMAT, UMR 6508, CNRS/ENSICAEN/UNICAEN,6 Boulevard Marechal Juin, 14050 Caen Cedex, France

2 Department of Chemistry, Visva-Bharati, Santiniketan-731235, West Bengal, India

Les systèmes magnétiques de basse dimensionnalité peuvent présenter une dynamique de spins suffisamment lente pour se comporter comme des « aimants » malgré l’absence de mise en ordre à longue portée (LRO). Ceci résulte de l’existence de grandes barrières d’énergie face au renversement des spins, conduisant à des temps de relaxation qui divergent à basse température. En 0D, ces barrières sont liées à l’anisotropie locale des ions, et donnent lieu aux comportements de Single-Molecule Magnet (SMM) et de Single-Ion Magnet (SIM). Dans les systèmes 1D, appelés Single-Chain Magnet (SCM), les barrières mettent aussi en jeu les couplages intrachaînes. Ces phénomènes sont encore aujourd’hui très majoritairement investigués dans des composés moléculaires. Il est même généralement admis que les composés inorganiques n’y sont pas favorables, enraison de leur plus grande propension à s’ordonner magnétiquement.

Or, nous avons récemment observé de claires signatures de SCM et SIM dans les composés Sr4-xCaxMn2CoO9. Ces oxydes ont une structure de chaînes organisées en réseau triangulaire, et possèdent toutes les caractéristiques de base nécessaires à l’obtention de ces comportements magnétiques particuliers. En outre, de simples substitutions permettent d’ajuster finement l’intensité des couplages par effet de pression chimique, et fournissent ainsi un cadre favorable pour étudier les relations entre SIM, SCM et LRO, ce qui est une question très débattue à l’heure actuelle.

Il apparait donc que certains oxydes pourraient être complémentaires des composés moléculaires dans l’investigation des « aimants 0D et 1D induits par effet de blocage », ce qui ouvre de nouvelles perspectives dans l’étude de ces phénomènes.

0 5 10 15 20 25 30 35 400.0

0.1

0.2

0.3

LRO

SIM

SCM

x=2

x=0

' (

emu/

mol

Oe)

T (K)

101 Hz

102 Hz

103 Hz

104 Hz



NMR investigation of the putative Bose-glass regime

in the doped DTN at high magnetic fields unveils the

existence of a new, impurity-induced BEC-type phase

Mladen Horvatić1, Anna Orlova1, Rémi Blinder1, Edwin Kermarrec1,

Maxime Dupont2, Nicolas Laflorencie2, Sylvain Capponi2,

Hadrien Mayaffre1, Claude Berthier1, Armando Paduan-Filho3

1LNCMI CNRS/EMFL/UGA/UPS/INSA, Grenoble, France 2LPT, CNRS/Université de Toulouse, Toulouse, France

3Instituto de Física, Universidade de São Paulo, São Paulo, Brazil

The NiCl2-4SC(NH2)2 compound, or DTN for short, is one of the most studied

archetype materials for the magnetic-field-induced 3D-ordered low-temperature phase

of the Bose-Einstein condensation (BEC) type. When DTN is disordered by doping with

Br, a localized, gapless Bose-glass (BG) phase is predicted to appear adjacent to the

BEC phase [1], replacing the gapped regime of the pure system. Br-doped DTN is thus

proposed as a unique thermodynamic model system for studying BG physics.

We have performed the first microscopic study [2], by nuclear magnetic resonance

(NMR), of this putative BG regime in doped DTN at high magnetic field, and found a

clear signature for a level crossing of the energy levels related to the localized,

doping-induced impurity states, at the nearly doping-independent field value H*

13.6 T. Observation of the local NMR signal from the spin adjacent to the doped Br

allowed us to fully characterize this impurity state and thus quantify a microscopic

theoretical model. The level-crossing of the impurity states and their interaction are then

providing the building blocks prone to create a new BEC-type order.

Indeed, a theoretical modelling [3], by quantum Monte Carlo simulation, have

confirmed this scenario: close to H* and at very low temperature, a localized BG regime

is replaced by a new, delocalized, fully-3D coherent “BEC*” phase. Predicted magnetic

field and doping dependence of this phase showed that it is experimentally accessible

for higher doping levels [3]. We have thus started a new NMR investigation of 13%

Br-doped DTN, and our preliminary data indeed detected the ordering transition at

Tc(H*) 0.15 K. The existence of this new, “order-from-disorder” phase is thus

definitely confirmed.

[1] R. Yu et al., Nature 489, 379 (2012).

[2] A. Orlova et al., Phys. Rev. Lett. 118, 067203 (2017).

[3] M. Dupont et al., Phys. Rev. Lett. 118, 067204 (2017).



Doped DTN at high fields – Theoretical surprise

Nicolas Laflorencie, Maxime Dupont, and Sylvain Capponi

LPT, CNRS/Universite de Toulouse, Toulouse, France

Building on the recent NMR investigation1 of the doped quasi-one-dimensionalS = 1 antiferromagnetic material Ni(Cl1−xBrx)2-4SC(NH2)2 (DTNX) at highmagnetic field, we propose a new theoretical description,2 which strongly con-trasts with earlier proposals.3 In particular, instead of the previously claimedBose Glass phase (a zero-temperature many-body localized state) at high mag-netic field, we predict a novel type of impurity-induced order with a globalquantum coherence over the full sample, yielding a new kind of Bose-Einsteincondensation.

Based on an effective model description of interacting impurities and large scalenumerical simulations of realistic quantum many-body Hamiltonians, the tem-perature - field phase diagram of DTNX is strongly reshaped, thus calling fornew experimental investigations.

Beyond the canonical Bose-Einstein Condensate (BEC) known for DTN between Hc1 = 2.1 T

and Hc2 = 12.3 T, a new type of condensate (BEC∗) exists in the vicinity of 13.6 T. This new

(disorder-induced) quantum state emerges out of the interaction between localized impurity

states, unveiled by a strong NMR relaxation peak as a function of the magnetic field.

1A. Orlova et al., Phys. Rev. Lett. 118, 067203 (2017)

2M. Dupont et al., Phys. Rev. Lett. 118, 067204 (2017).

3R. Yu et al., Nature 489, 379 (2012).



Supraconductivité II

42

Evidences of orbital-selective correlations in themeasured gap structure in FeSe

Luca de’ Medici1

1ESPCI, Paris, France

A recent report of Bogoliubov quasiparticle interference measurements on FeSesingle crystals traces the angular dependence and sign of the superconductinggaps with unprecedented precision. Fitting these gap structures with existingpairing theories fails, the missing piece being strongly orbital-selective quasipar-ticle weights. These have been predicted in the recent years as a general featureof Hund’s correlated metals.

Sprau et al., Discovery of Orbital-Selective Cooper Pairing in FeSe, ArXiv:1611.02134



Superconductivity in the iron-based hydride LaFeSiH

Sophie Tencé1, Fabio Bernardini

2, Gaston Garbarino

3, André Sulpice

4, Manuel

Nuñez-Regueiro4, Etienne Gaudin

1, Bernard Chevalier

1, Andrés Cano

1

1CNRS, Univ. Bordeaux, ICMCB, UPR9048, Pessac, France

2CNR-IOM-Cagliari, Dipartimento di Fisica, Universita di Cagliari, Monserrato, Italy

3European Synchrotron Radiation Facility, Grenoble, France

4CNRS, Université de Grenoble, Institut Néel, Grenoble, France

Since the discovery of unconventional superconductivity in Fe-based materials in 2008,

Fe-based superconductors (Fe-SC) have attracted much attention and have been the

subject of intense and systematic investigations. To date, Fe-SC always contain

pnictogen or chalcogen elements (P, As and Se, Te respectively). Besides, they are

usually obtained by solid state reaction with possibly the use of high pressure.

In this context, we have recently synthesized the new hydride LaFeSiH by solid-gas

hydrogenation of the precursor LaFeSi. Preliminary results show that this hydride is

isostructural to the 1111 Fe-SC compounds and displays superconductivity below 8.5 K

(see Figure). This hydride also presents other structural, magnetic and electronic

similarities with the previously reported Fe-SC compounds. In particular, LaFeSiH

undergoes a transition from tetragonal to orthorhombic structure at low temperature,

distortion which is suppressed by an external pressure and re-emerges at higher pressure.

In addition, DFT calculations have evidenced the quasi-2D character of the Fermi

surface with a dominant contribution of the 3d(Fe) orbitals. These calculations also

predict the onset of a single-stripe antiferromagnetic order that would explain the

orthorhombic distortion. Therefore, LaFeSiH can be considered as the first Fe-SC

obtained by solid-gas hydrogenation and free from toxic pnictogen and chalcogen

elements.

Figure. Normalized magnetization as a function of the magnetic field at 2 K (left)

and as a function of the temperature at 10 and 2 Oe (right).



Détermination du paramètre d’ordre supraconducteur

de FeSe à partir de mesures thermodynamiques,

magnétiques et spectroscopiques couplées

Hervé Cercellier1,2

, Pierre Rodière1,2

, Pierre Toulemonde1,2

, Christophe Marcenat1,3

,

Thierry Klein1,2

1Univ Grenoble Alpes, Inst. NEEL, F-38000 Grenoble, France

2CNRS, Inst NEEL, F-38000 Grenoble, France

3CEA, INAC, PHELIQS, F-38000 Grenoble, France

En dépit de sa simplicité chimique et structurale, le supraconducteur FeSe

possède des propriétés physiques complexes. Malgré l’absence d’un ordre magnétique à

longue portée à basse température, FeSe présente une transition structurale à TS=90K et

l’apparition d’un ordre orbital nématique dont la structure et l’origine, ainsi que son lien

avec la transition supraconductrice, sont fortement débattus. Dans l’état

supraconducteur, il est établi que FeSe est un système multi-bandes, mais l’amplitude,

le signe et l’anisotropie des paramètres d’ordre ne sont pas encore clairement

déterminés. De plus, le libre parcours moyen des quasi-particules est extrêmement

grand (Li et al., New. J. Phys. 18, 082001 (2016)), ce qui suggère que les effets de

« pair-breaking » sont négligeables dans FeSe, à l’opposé de ce qui est observé dans les

autres chalcogénures et pnictures de fer.

Nous présentons une étude des propriétés supraconductrices du composé FeSe

par mesures couplées de spectroscopie de réflexion Andreev, chaleur spécifique et

longueur de pénétration magnétique. Les mesures établissent sans ambiguïté le caractère

multi-gap de FeSe, ainsi que l’absence de noeud dans le paramètre d’ordre

contrairement à ce que suggéraient les premières mesures STM/spectroscopie tunnel

(Song et al. Science 332, 1410 (2011)) ou de longueur de pénétration de London

(Kasahara et al. PNAS 111, 16309 (2014)). Une modélisation simultanée des trois types

de mesures avec un modèle à deux gaps suggère l’existence d’un petit gap fortement

anisotrope de valeur moyenne ΔS 0.6 kBTc et d’un grand gap faiblement anisotrope de

valeur moyenne ΔL 2 kBTc. Enfin, nous montrons comment les mesures couplées

permettent de reconstruire la relation entre la surface de Fermi et les gaps

supraconducteurs. Ces résultats sont compatibles avec l’hypothèse d’un appariement

des paires de Cooper fortement dépendant du caractère orbitalaire des électrons à la

surface de Fermi.



Tuning of the phase diagram and quantum critical point by disordered in Fe-based

superconductors.

Marcin Konczykowski1, Yuta Mizukami

2, Takasada Shibauchi

2, Shigeru Kasahara

3,

Yuji Matsuda3

1Laboratoire des Solides Irradiés, Ecole Polytechnique, 91128 Palaiseau, France

2Department of Advanced Materials Science, University of Tokyo, Japan

3Department of Physics, Kyoto University, Kyoto 606-8502, Japan

Typical composition – temperature phase diagram of Fe-based superconductors shows dome

shaped superconducting region, intersected by magnetic transition line. Other classes of

materials: high temperature superconductors, doped Mott insulators and heavy fermions

exhibit similar diagrams commonly interpreted as the signature of quantum critical point

(QCP) lying beneath superconducting dome. Fluctuations in the vicinity of QCP seem to give

rise to nonconventional superconducting pairing, however this effect remains elusive.

Here we explore the effect of crystalline (point like) disorder on the entire phase diagram of

canonical iron based superconductor Ba(FeAs1-xPx)2. Beyond the strong suppression of

critical temperature and of the change of topology of superconducting gap by point like

disorder (introduced by low temperature electron irradiation) reported previously [1] we

found depression of spin density wave (SDW) transition and extension to lower temperatures

of non-Fermi liquid behavior in disordered samples. This observation points to possible shift

of QCP by disorder synchronized with displacement of the superconducting dome and direct

link between QCP and superconducting transition (SC) [2].

In the underdoped region of the phase diagram, we observe on cooling sequential SDW and

SC transitions. Superconducting state emerges from antiferromagnetic state leading to

singular vortex core. In this region we found

fingerprints of novel transition inside of

superconducting dome indicating two

different superconducting phases. The

sequence of transition from para- to

antiferromagnetic state can be tuned by

disorder to direct transition from

paramagnetic to superconducting state.

Finally, we explore the evolution of SDW

transition with point and correlated disorder

in parent compound Ba(FeAs)2. We observe

strong downward shift of the SDW

transition temperature. Detailed analysis of

Hall coefficient vs. T variations at different

disorder levels shows that transition remains

sharp and SDW transition is robust against

disorder.

[1] Y. Mizukami et al., Nature Comm. 5,

5657 (2014)

[2] Y. Mizukami et al., submitted to PNAS Fig.1. Shift of SDW and SC transition by Irradiation-induced disorder



Stick-slip Phenomena and Memory Effects in MovingVortex Matter

Lise Serrier-Garcia1,2,*, Clécio C. de Souza Silva3, Matias Timmerman2, Joris Van de Vondel2 and Victor V. Moshchalkov2

1 LPS – Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay Cedex, France 2 INPAC – Institute for Nanoscale Physics and Chemistry, KU Leuven, , B–3001 Leuven, Belgium

3 Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901 Recife, Brazil.

Elastic deformations of 3D objects in a viscous medium directly impact many different systems such as polymers, Fermi gases, glass-forming liquids and plasma crystals. In the case of superconducting condensates, the defects intrinsically present in natural or artificial materials substantially modify the elastic moduli of the vortex lattice. The theoretical and experimental efforts done on the topics were intense in the 90’s but they were performed quasi exclusively on high-Tc superconductors using global techniques, consequently revealing specific vortex dynamics and pinning with discrepancy. However, Auslaender et al. succeeded in moving vortices one by one by means of a magnetic tip in the cuprate YBaCuO and proved that the anisotropy in the vortex displacement is determined by the chains of oxygen vacancy like the anisotropy of superconducting gap. In the conventional superconductor NbSe2, scanning tunneling microscopy (STM) was used to directly image moving vortex lattices, confirming the peak effect analysis as a melting transition from an elastic phase to a plastic phase. These experiments are ones of the few carried with individually-probed vortex techniques necessary to validate the microscopictheories. Recently, we have developed a new operating mode of the conventional STM technique to observe periodic vortex core trajectories with spatial and temporal resolution. A periodic motion is probed using an extended version of the so-called “Lazy fisherman method”, in which a fisherman (STM tip) waits at a fixed position for a fish (vortex) to pass by. This method synchronized to the external excitation gives access to the individual trajectory in real-time and is applicable to virtually any scanning probe microscopy. Here, we use this new technique to explore the vortex dynamics in interplay with the natural weak pinning landscape in NbSe2. We evidence at low drive the linear and collective motion of a Bragg vortex glass in the so-called Campbell regime, while at high drives the trajectories present striking nonlinear trajectories with a pinning-depinning process unrelated to local defects. Performing three-dimensional Langevin dynamics simulations, we demonstrate that the specific nonlinearity of the second regime is a stick-slip motion related to the collective pinning and the periodicity of the lattice. We additionally explore the impact of initial conditions at the transition between the two regimes and reveal an enhancement of the long-range correlations with the ac magnetic field cooling procedure. The success of this work opens new possibilities to solve issues such as the dynamical channels related to the wave density charge in Nbse2 or the memory effects in high-Tc superconductors.

Figure 1| The synchronized Lazy-Fisherman STM spectroscopy is used to probe ac-driven vortices in NbSe2 at 0.5 K.



Two-dimensional topological superconductivity in

Pb/Co/Si(111)

Gerbold C. Ménard1, Sébastien Guissart2, Christophe Brun1, Mircea

Trif2, François Debontridder1, Raphaël T. Leriche1, Dominique

Demaille1, Dimitri1,3, Pascal Simon2 and Tristan Cren1 1Institut des Nanosciences de Paris, Université Pierre et Marie Curie

(UPMC),CNRS-UMR 7588, 4 place Jussieu, 75252 Paris, France 2Affiliation Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université

Paris-Saclay, 91405 Orsay Cedex, France 3Laboratoire de physique et d’étude des matériaux, LPEM-UMR8213/CNRS-ESPCI

ParisTech-UPMC, 10 rue Vauquelin, 75005 Paris, France

Majorana fermions are very peculiar quasiparticles that are their own antiparticle. They

obey non-abelian statistics: upon exchange, they behave differently from fermions

(antisymmetric) and bosons (symmetric). Their unique properties could be used to

develop new kind of quantum computing schemes. Majorana states are predicted to

appear as edge states of topological superconductors, in a similar way as Dirac surface

states appears at the edge of topological insulators. Spectroscopic signatures of

Majorana bound states were claimed to be observed in one-dimensional (1D) InAs

nanowires proximity-coupled to a bulk superconductor. Then Nadj-Perge et al. [1] have

realized a chain of Fe adatoms on a Pb(110) crystal that is supposed to induce locally a

1D topological p-wave superconductivity. Zero-energy bound states were observed at

the extremity of some the Fe chain and claimed to be interpreted as Majorana

excitations [1]. Nevertheless this interpretation is challenged by close to zero-energy

Shiba states [2].

We have recently decided to follow a different strategy using sizeable magnetic disks

made of Cobalt buried under a superconducting monolayer of Pb grown on Si(111). We

have observed that dispersive edge states appear in the superconducting gap around the

magnetic domains [3]. We have interpreted these spectroscopic features as signatures of

a locally induced topological superconductivity in our 2D system consisting in

Pb/Co/Si(111). Indeed, we expect to get some propagative Majorana edge states around

2D topological domains since the edges have a 1D character. This is at odds with the Fe

chains whose edge states are intrinsically 0D and are thus characterized by

non-propagative bound states.

[1] S. Nadj-Perge, I. K. Drozdov, J. Li, H. Chen, S. Jeon, J. Seo, A. H. MacDonald, B.

A. Bernevig, and A. Yazdani, Science 346, 602 (2014).

[2] M. Ruby, F. Pientka, Y. Peng, F. Von Oppen, B.W. Heinrich, and K. Franke, PRL

115, 197204 (2015).

[3] G. C. Ménard, S. Guissart, C. Brun, M. Trif, F. Debontridder, R. T. Leriche, D.

Demaille, D. Roditchev, P. Simon, T. Cren, arXiv:1607.06353 (2016).



Electrostatic modulation of superconductivity infew nm Bi2Sr2CaCu2O8+xfilms

Edoardo Sterpetti1, Johan Biscaras1 and Abhay Shukla1

1 Institut de Mineralogie, de Physique des Materiaux et de Cosmochimie,UPMC Univ. Paris 06, UMR CNRS 7590, MNHN, IRD UMR 206, 4 Place

Jussieu, F-75005 Paris, France

Ultrathin Bi2Sr2CaCu2O8+x(Bi2212) films with thickness varying from 1 to2 unit cells were prepared on glass substrates by anodic bonding [1, 2], froman optimally doped precursor single crystal. The as-prepared samples exhibitedcritical temperatures ranging from 81K to 51 K. These were doped electro-statically using the Space Charge Doping method [3, 4], to vary the criticaltemperature (Tc) in a reversible manner. We show results of low temperaturetransport measurements as a function of electrostatic doping. We discuss themodification of Tc, estimations of the variation of carrier concentration and therepercussion of these on the phase diagram.

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 00

2

4

6

8

1 0

R S(kΩ/

)

+ V G

T ( K )

- V G

V G

Figure 1: Modulation of normal state and superconductivity by electrostatic dopingin ultrathin Bi2Sr2CaCu2O8+xfilms

References

[1] Gacem, K., Boukhicha, M., Chen, Z., and Shukla, A. Nanotechnology23(505709) (2012).

[2] Shukla, A., Kumar, R., Mazher, J., and Balan, A. Solid State Communica-tions 149(17-18), 718–721 (2009).

[3] Paradisi, A., Biscaras, J., and Shukla, A. Appl. Phys. Lett. 143103 (2015).

[4] Biscaras, J., Chen, Z., Paradisi, A., and Shukla, A. Nature Communications6, 1–8 (2015).



Quantum criticality, superconductivity andFermi surface dimensionality - comparison of

CeIn3, CeRhIn5, and CePt2In7

Y. Krupko1, S. Ota2, Y. Hirose2, R. Settai2, A. Demuer1, K. Gotze3,J. Klotz3, T. Foster3, J.A.N. Bruin4, A. McCollam4, H. Harima5, M. Raba1,6,E. Ressouche7, N. Qureshi8, C.V. Colin6, V. Nassif6, P. Rodiere6, I. Sheikin1

1LNCMI, CNRS, UGA, Grenoble, France

2Department of Physics, Niigata University, Niigata, Japan

3HLD, HZDR, Dresden, Germany

4HFML, Radboud University, 6525 ED Nijmegen, The Netherlands

5Graduate School of Science, Kobe University, Kobe 657-8501, Japan

6Institut Neel, CNRS, UGA, Grenoble, France

7INAC, CEA, UGA, Grenoble, France

8ILL, Grenoble, France

CePt2In7 is a recently discovered heavy fermion antiferromagnet with a Neeltemperature TN = 5.5 K. It belongs to the same family of CeTnIn2n+3 (T :transition metal) systems as the well-studied CeIn3 and CeRhIn5. The crystalstructure of these materials consists of a sequence of CeIn3 layers intercalatedby n T In2 layers along the c axis. All three compounds, antiferromagnets undernormal conditions, can be tuned to a quantum critical point by either pressureor magnetic field. Although their Neel temperatures differ considerably, thecritical values of the tuning parameters are similar, Pc ∼ 2.5 − 3.5 GPa andHc ∼ 50 − 60 T. Furthermore, an unconventional superconductivity emerges inthe vicinity of a pressure-induced quantum critical point in all three materials.

In heavy-fermion compounds, the Fermi surface dimensionality is expected toinfluence both the superconducting critical temperature and the type of quan-tum criticality, although this issue is still somewhat controversial. While theFermi surface is almost spherical in the anisotropic CeIn3, that of CePt2In7 isalmost ideally two-dimensional, with CeRhIn5 located somewhat in between. Iwill compare the Fermi surfaces in all three materials and discuss their supercon-ducting properties and Fermi surface reconstructions associated with quantumcriticalities from this perspective.



Vulgarisation

51

Vulgariser la matière condensée : pourquoi ? comment ?

Julien Bobroff

Laboratoire de Physique des Solides, Université Paris-Sud, CNRS

Le manque d’écho au prix Nobel de physique 2016 sur la topologie révèle la difficulté de

vulgariser certains aspects de la physique des solides. Mais il révèle peut-être aussi un certain

manque d’engagement de notre communauté dans ce travail d’explication vers le grand

public et les médias. Il y a de bonnes raisons pour cela, la physique en jeu d’abord, pas

simple à expliquer, mais aussi le manque de temps, de moyens, d’effets sur sa carrière…

Pour les plus motivés, il existe pourtant des solutions pour contourner ces obstacles.

J’argumenterai pourquoi notre communauté doit plus se mobiliser sur ces enjeux de

vulgarisation, et comment elle pourrait s’y prendre collectivement et individuellement pour

changer la donne. J’illustrerai mes propos avec quelques exemples récents issus de nos

propres productions sur plusieurs des sujets du GDR, y compris la topologie !



Phénomènes emergents, corrélations, etdynamique

53

Kondo effect: an old problem, some new aspects

Claudine Lacroix

Institut Néel, CNRS et UGA, Grenoble

Kondo effect was discovered more than 50 years ago, and it is still a very active field

of research with implications in a large variety of systems. After the 1st explanation by

Kondo, the single impurity Kondo model was a playground for many new theoretical

techniques in the years 1970-1990. Many extensions of this model have been studied to

describe magnetic and superconducting properties of heavy fermions, and in the last 20

years, Kondo effect in quantum dots has been a very active topics.

In this talk, I will make a short historical review and describe several actual topics

related to Kondo effect, and motivated by the the study of new compounds.

meeticc2017 - - Vendredi 31 mars 2017 - 8:45/9:25 (40min)


Electric field induced Insulator to Metal Transition in

Mott insulators

B. Corraze1, J. Tranchant

1, M.P. Besland

1, C. Adda

1, P. Diener

1, L. Cario

1, E. Janod

1

1 Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la

Houssinière, BP 32229,44322 Nantes Cedex 3, France.

Bien que les systèmes fortement corrélés aient été intensément étudiés durant ces

dernières décennies, très peu d’applications basées sur ces composés ont vu le jour.

Récemment, la possibilité de piloter la résistance de ces matériaux par le champ

électrique ou par impulsion laser via une transition de phase « purement » électronique

(c'est-à-dire potentiellement ultra rapide) a ouvert un vaste champ applicatif dans le

domaine de la microélectronique et notamment des mémoires RRAM.

Dans cet exposé, après un bref rappel des conditions requises pour obtenir un état

« isolant de Mott », nous passerons en revue différents exemples de systèmes fortement

corrélés dans lesquels une transition isolant-métal induite par champ électrique a été

observée. A partir de ces exemples, nous nous interrogerons sur la nature de la transition :

Est-elle en volume ou filamentaire ? Quel est le rôle du chauffage ? Nous montrerons

ensuite que certaines caractéristiques communes peuvent être dégagées (voir Fig1). Enfin

nous verrons qu’un modèle théorique développé par Fröhlich pour les semi-conducteurs

dans les années 1930-1940 concorde parfaitement avec les résultats expérimentaux

récents et permet donc d’avoir une vision, tout du moins partielle, du mécanisme

microscopique mis en jeu.

+ si affinité (ou temps) : Un exemple d’application possible pourra être détaillé.

Fig 1 : Caractéristiques I-V de différents isolants de Mott lors de la transition

isolant-métal induite par champ électrique



Transition Isolant de Mott-Métal dans Sr2IrO4

A. Louat1, V. Brouet1, L. Serrier-Brinon1, F. Bert1, F. Bertran2, P. Le Fèvre2,J. Rault2

1Laboratoire de Physique des Solides, CNRS, Univ. Paris-Sud, Université

Paris-Saclay, 91405 Orsay Cedex, France2Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP 48, 91192 Gif

sur Yvette, France

On s'attend à priori à une diminution des correlations lors du passage d'unélément 3d à un 5d car les orbitales 5d sont plus étendues que les 3d. D'un autrecôté, le couplage spin-orbite est fort pour les éléments 5d et peut changer cettevision. En eet, le composé Sr2IrO4, avec 5 électrons sur une couche 5d, estisolant et est considéré comme l'archétype des isolants de Mott induit par unfort couplage spin-orbite1.Nous avons étudié par Spectroscopie par PhotoÉmission Résolue en Angle (ARPES)comment se passe cette transition dans le cas d'une substitution de Ir par duRh dans ce nouveau type d'isolant de Mott. L'évolution de la résistivité jusqu'àl'état métallique est présenté Fig. 1. Malgré le fait que Rh est isovalent à l'iri-dium, il semble induire un dopage eectif en trous2,3. Par photoémission, nousobservons un décalage du niveau de Fermi vers la plus haute bande pleine (Lo-wer Hubbard Band), l'apparition de poche de trou au point X (voir la Surfacede Fermi en Fig. 2 pour un dopage de 15% en Rh), mais la persistance d'un pseudo-gap résiduel et l'absence de pic de quasi-particule. Nous discuteronsle rôle du Rh dans la transition et la nature de l'état métallique induit.

Fig. 1 Résistivité deSr2(Ir1−xRhx)O4 pour x allantde 0.02 à 0.15. Une transitionIsolant-Métal est visible à environ7% de Rh.

Fig. 2 Surface de Fermi deSr2(Ir0.85Rh0.15)O4. Des pochesde trous sont présentes autour despoints X.

1. B. J. Kim et al., Phys. Rev. L 101, 076402 (2008)

2. J. P. Clancy et al., Phys. Rev. B 89, 054409 (2014)

3. Y. Cao et al., Nature Communications 7, 11367 (2016)



Transition isolant métal induite par pression dans l'isolant de Mott moléculaire organique [Au(Et-thiazdt)2].

Benjamin Brière 1, Jonathan Caillaux1 , Andréa Perucchi4, Stefano Lupi3, Rodolphe Sopracase1 , Jean-Claude Soret1 , Nathalie Tenn2, Dominique Lorcy2 et Vinh Ta Phuoc 1

1 GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Parc de Grandmont, 37200 Tours, France

2 Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1,Matière Condensée et Systèmes Electroactifs (MaCSE),Campus de Beaulieu, Bât 10A, 35042 Rennes cedex, France

3 CNR-IOM and Department of Physics, Sapienza University of Rome,P.le A. Moro 2, 00185 Rome, Italy

4 Synchrotrone Elettra Trieste S.C.p.A., Area Science Park,34012 Basovizza, Trieste, Italy

L'isolant de Mott moléculaire organique quasi 2D [Au(Et-thiazdt)2] présente une transition métal isolant induite par l'application d'un pulse électrique ou d'une pression externe. Afin de comprendre les mécanismes à l'origine de cette transition, nous avons étudié les propriétés optiques de [Au(Et-thiazdt)2] par spectroscopie infrarouge à haute pression et à température ambiante. Les résultats expérimentaux ont permis de mettre clairement en évidence un comportement métallique au-dessus de 1.5 GPa, caractérisé par l'apparition d'un pic de Drude et une évolution du poids spectral fortement anisotrope dans les spectres de conductivité optique. Suivant la direction d'empilement des molécules, nous avons observé une forte augmentation du poids spectral en dessous de 1 eV, alors que dans la direction transverse, la conductivité optique est caractérisée par un transfert de poids spectral du moyen infrarouge vers les basses énergies. Les calculs DFT montrent deux bandes de caractère SOMO (Singly Occupied Molecular Orbital) au voisinage du niveau de Fermi à pression ambiante. À haute pression, outre un élargissement des bandes SOMO, une bande de caractère SOMO-1 vient couper le niveau de Fermi. Il en résulte que la transition isolant- métal induite sous pression est simultanément une transition de Mott de type "bandwidth controlled" et "bandfilling controlled". De plus, la phase métallique de haute pression possède à la fois des porteurs corrélés et non corrélés. Par ailleurs, la conductivité optique calculée permet de reproduire qualitativement l'évolution des spectres expérimentaux en fonction de la pression appliquée.



Instabilités structurales et électroniques des

bronzes phosphates de tungstène

Alain Pautrat1, Elen Duverger-Nedelec1, Kamil Kolincio2 et Olivier Pérez1 1 Laboratoire CRISMAT, ENSICaen, CNRS UMR 6508, Caen, France 2 Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland

Les conducteurs à basse dimensionnalité sont le siège de propriétés remarquables :

supraconductivité HTc, transitions métal isolant de type onde de densité de charge

(ODC), fortes mobilité électroniques et effets magnétorésistifs associés... Les bronzes

phosphates de tungstène font partie d’une vaste famille de composés à propriétés

électroniques quasi-2D, avec une anisotropie et un taux de porteurs modulables selon le

membre de la famille, et l’apparition de modulations structurales

commensurable/incommensurable à basse température interprétées comme des états de

Peierls (ODC) (e.g, P. Foury, J.P. Pouget, E. Wang, M. Greenblatt, Journal de

Physique IV, colloque C2, V3, 133 (1993)). Le terme limite de la famille WO3 est un

isolant antiferroélectrique. Le lien structure/propriété est particulièrement présent dans

cette famille et permets une collaboration naturelle entre chimistes du

solide/cristallographes/physiciens.

Nous présenterons nos résultats récents sur certains membres de cette famille en se

focalisant sur 1/ La possibilité d’utiliser cette famille pour mieux comprendre la

problématique de couplage fort/faible des ODC ; 2/ L’origine des propriétés

électroniques remarquables observées comme de très fortes oscillations quantiques. Les

premières mesures sur les états supraconducteurs observés à basse température seront

abordées. ( K.Kolincio et al, Phys. Rev. B, 2016, 94 (24) rapid com; Phys. Rev. B,

2016, 93 (23))

0 2 4 6 8-0.005

0.000

0.005

0.010

0.015

MR

B (T)

20K

18K

16K

14K

12K

10K

8K

6K

4K

1.8K

Apparition de fortes oscillations de Shubnikov

de Haas dans Nax P4W20O68



Determination of the magnetic structure of CePt2In7 by

means of neutron diffraction

M. Raba,1, 2, 3

E. Ressouche,4 N. Qureshi,

5 C. V. Colin,

2, 3 V. Nassif,

2, 3

S. Ota,6 Y. Hirose,

7 R. Settai,

7 P. Rodière,

2, 3 and I. Sheikin

1

1Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), CNRS, UGA, 38042

Grenoble, France 2Université Grenoble Alpes, Institut Néel, F-38000 Grenoble, France

3CNRS, Institut Néel, F-38000 Grenoble, France

4INAC, CEA and Univ. Grenoble Alpes, CEA Grenoble, F-38054 Grenoble, France

5Institut Laue Langevin, 71 rue des Martyrs, BP156, 38042 Grenoble Cedex 9, France

6Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan

7Department of Physics, Niigata University, Niigata 950-2181, Japan

CePt2In7 is a recently discovered heavy fermion material belonging to the same family as the

well-known CeIn3 and CeRhIn5 compounds. However, the spacing between Ce-In planes in CePt2In7 is

drastically increased1 as compared to its CeRhIn5 counterparts, implying a more two-dimensional

crystal structure.

While the magnetic structure of the cubic CeIn3 is characterized by

a simple commensurate ordering wave vector (1/2, 1/2, 1/2)2, that of

the more two-dimensional CeRhIn5 is more complicated. Its

magnetically ordered ground state is an incommensurate helicoidal

phase with the propagation vector qM = (1/2, 1/2, 0.297) and the

magnetic moment in the basal plane of the tetragonal structure3.

The magnetic structure of its antiferromagnetic (AF) ground state is

still an open question. The existing reports on this matter are

controversial: some of them exhibit a coexistence of commensurate

and an incommensurate4 AF orders while others show a

commensurate5 order only. All these experiments lead to the same

conclusion: the magnetic propagation vector is (1/2, 1/2, δ),

although the value of δ is not predicted.

I will present determination of the magnetic structure of the heavy

fermion antiferromagnet CePt2In7 by single crystal neutron

diffraction. We find a magnetic wave vector qM = (1/2, 1/2, 1/2),

which is temperature independent up to TN = 5.5 K. A staggered

moment of 0.45(1)μB at 2 K resides on the Ce ion. The

nearest-neighbor moments in the tetragonal basal plane are aligned

antiferromagnetically. The moments rotate by 90° from one CeIn3

plane to another along the c-axis (see figure).

References

1 T. Klimczuk et al., J. Phys.: Condens. Matter 26 (2014) 402201 (5pp)

2 A. Benoit et al., Solid State Communications 34, 293 (1980).

3 W. Bao et al., Phys. Rev. B 62, R14621 (2000).

4 H. Sakai et al., Phys. Rev. B 83, 140408 (2011).

5 N. apRoberts Warren et al., Phys. Rev. B 81, 180403 (2010).

Figure. Crystal structure of

CePt2In7 (Ce: yellow, Pt: grey,

In: purple) with magnetic

moments (red arrows).



Neutron diffraction study of CeRh2Si2 underpulsed magnetic field

C. M. N. Kumar1, W. Knafo1, F. Duc1, F. Bourdarot2, D. Aoki3,4,J. Flouquet4, L.-P. Regnault5

1Laboratoire National des Champs Magnetiques Intenses,CNRS-INSA-UJF-UPS, Toulouse, France

2Service de Modelisation et d’Exploration des Materiaux, Universite GrenobleAlpes et Commissariat a l’Energie Atomique, INAC, Grenoble, France

3Institute for Materials Research, Tohoku University, Ibaraki, Japan

4Service Photonique, Electronique et Ingenierie Quantiques, UniversiteGrenoble Alpes et Commissariat a l’Energie Atomique, INAC, Grenoble,

France

5Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble,France

We present a single crystal neutron diffraction study of the heavy–fermion an-tiferromagnet CeRh2Si2 performed in high fields of up to 30 T. This systemis antiferromagnetic below TN = 36 K, with a change of magnetic state belowT1,2 = 26 K [1]. Under a magnetic field a third antiferromagnetic phase, AF3 isstabilized between µ0H2,3 ≈ 25.5 T and µ0Hc ≈ 26 T, above which the system ispolarized paramagnetically [2]. A new long–duration (>100 ms) and high dutycycle, 40–T conical pulsed magnet developed by the LNCMI–Toulouse, the CEAGrenoble and the ILL Grenoble, has been used on the triple–axis spectrometerIN22 (CRG–CEA at the ILL). The magnetic structure in AF3 phase has beendetermined here. In the discussion we will compare the effects of pressure andmagnetic field on CeRh2Si2.

[1] S. Kawarazaki, M. Sato, Y. Miyako, N. Chigusa, K. Watanabe, N. Metoki,Y. Koike, and M. Nishi, Phys. Rev. B 61 4167 (2000).

[2] W. Knafo, D. Aoki, D. Vignolles, B. Vignolle, Y. Klein, C. Jaudet, A. Vil-laume, C. Proust, and J. Flouquet, Phys. Rev. B 81 094403 (2010).



Electron-phonon coupling in a molecular crystalκ-(BEDT-TTF)2Cu2(CN)3

measured by Resonant Inelastic X-ray Scattering

Vita Ilakovac1,2, Pascale Foury-Leylekian3, Alessandro Nicolaou4, Silvia Tomić5, Stephane Carniato1, Jean-Paul Pouget3, Predrag Lazić6, K. Miyagawa7, K. Kanoda7

1 Sorbonne Universités, UPMC, LCPMR, CNRS UMR 7614, 4 pl. Jussieu, F-752312 Université de Cergy-Pontoise, F-95031 Cergy-Pontoise, France3 Laboratoire de Physique de Solides, CNRS UMR 8502, Orsay, France 4 Synchrotron SOLEIL, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France5 Institut za fiziku, P.O.Box 304, HR-10001 Zagreb, Croatia6 Rudjer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia7 Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan

Effects of the electron-phonon coupling are omnipresent in condensed matter physics, the most spectacular being the conventional superconductivity. But, there are only few experimental techniques permitting to measure its strength. Improvement of the resolving power of the resonant x-ray scattering (RIXS), promotes it to an excellent technique for direct electron-phonon coupling measurement, which is at the same time element-specific and momentum-resolved.

We measured RIXS of a molecular crystal κ-(BEDT-TTF)2Cu2(CN)3. This charge transfer salt is known as the most prominent spin-liquid Mott insulator. Moreover, a low pressure of the order of 1 kbar suppresses its Mott insulating state and establishes a superconducting state. It is constituted of layers of organic BEDT-TTF molecules separated by Cu2(CN)3 anion planes. Understanding how the lattice dynamics couples to its charge and spin degrees of freedom is of primary importance, as neither the spin-liquid state nor the superconducting state are not yet completely understood.

N K edge RIXS spectra of κ-(BEDT-TTF)2Cu2(CN)3 show a clearly resolved vibrational progression in the quasi-elastic part of the spectra. The separation of harmonics of about 250 meV is attributed to the excitation of the CN stretching mode. After IR and Raman techniques, the electron-phonon coupling strength of this Einstein phonon is considered to be negligible. Using RIXS, we estimated the value of its dimensionless electron phonon coupling constant with success.



Poster

63

Comportement exotique des vortex dans un

supraconducteur conventionel: le Niobium

Alain Pautrat 1, Muhamad Aburas

1, Joseph Scola

2, Annie Brûlet

3

1

Laboratoire CRISMAT, Caen, France 2

Laboratoire GEMAC, Versailles, France 3

LLB Saclay, France

La physique des réseaux de vortex est à la fois un sujet très fondamental lié à la

dynamique des systèmes désordonnés, et un sujet d’intérêt technologique car les

propriétés électromagnétiques d’un supraconducteur sont pilotées par cette même

physique. De nombreuses études des propriétés magnétiques et de transport se sont

concentrées dans l’état mixte supraconducteur Bc1<B<Bc2. Plus rares ont été celles dans

deux cas limites : le régime de supraconductivité de surface B>Bc2 où seule une petite

enveloppe supraconductrice survit, et l’état mixte intermédiaire B~Bc1. Afin de mieux

appréhender les propriétés et les signatures expérimentales d’une fine enveloppe

supraconductrice (avec un regain d’intérêt possible du aux thématiques de

supraconductivité topologique, d’interface…), nous avons repris l’étude d’un

supraconducteur à la fois conventionnel mais toujours plein de surprise: le Niobium.

Les propriétés de transport/bruit/magnétisme seront discutées, en se focalisant sur la

transition entre les supraconductivités volumiques et de surface et la possibilité de

différencier les deux phases en se basant sur les mesures de propriétés macroscopiques.

Par des mesures originales diffusion neutronique aux très petits angles, nous montrons

également que les premiers vortex qui se nucléent en volume dans la limite des très

faibles champs magnétiques subissent une interaction attractive avant de former un

réseau d’Abrikosov conventionnel.

0 1000 2000 30000.1

1

10

100

0 500 1000 1500 2000 2500 30000

1

2

a0 ~ 139 nm

i c(#

4)/

ic(#

1)

B (G)

i c (

A/c

m)

B (G)

sample #1

sample #4

Courant critique dans du Niobium, avec un

poli de surface modéré (point rouge), et

intense (point blanc) (T=6K, Bc2~1900G)

Cliché de diffusion neutronique dans l’état

mixte intermédiaire des vortex dans du

Niobium pur (T=6K, B=100G)



Densités de charge et de spin experimentales de la

perovskite YTiO3 obtenues par affinement joint.

Nicolas Claiser1, Ariste Bolivard Voufack

1, Mohamed Souhassou

1, Claude Lecomte

1,

Zeyin Yan2, Jean-Michel Gillet

2, Iurii Kibalin

1,3, Arsen Gukasov

3, Florence Porcher

3,

Béatrice Gillon3, Masahisa Ito

4

1CRM2, Université De Lorraine/CNRS, Vandoeuvre-lès-nancy, France,

2 SPMS UMR8580, CentraleSupelec, Université Paris-Saclay, Chatenay-Malabry,

France,3LLB, CEA-CNRS, CEA Saclay, Gif-sur-Yvette, France,

4Gunma University, Kiryu 1-5-1, Gunma, Japan

Notre étude porte sur la pérovskite YTiO3 qui présente un ordre de spin

ferromagnétique accompagné d’un ordre orbital antiferromagnétique en dessous de 30

K. A partir de mesures de diffraction rayons X à haute résolution (ligne BL 02 B1 à

Spring8, 20 K) et de diffraction de neutrons polarisés (LLB Saclay, 5 K), nous avons

construit un modèle expérimental commun de densité électronique (Deutsch et al.

IUCrJ (2014) 1,194–199) affiné conjointement sur ces différentes données. Ce modèle

permet de décrire les densités de charge et de spin de ce matériau en dessous de la

température de transition et autorise une exploration plus fine des origines de son

comportement singulier.

Cette affiche présentera les spécificités de la méthode, en particulier dans le cas de ce

cristal présentant une absorption importante et sujet à l’extinction. En nous appuyant en

parallèle sur des calculs théoriques, nous décrirons l’état électronique de ce matériau à

très basse température.



Diagramme de phase magnétique de CePt2In7 par

chaleur spécifique sous champs magnétiques intenses

Albin De Muer 1

, Ilya Sheikin1, Y. Krupko

1, S. Ota

2, Y. Hirose

3, R. Settai

3

1Laboratoire National des Champs Magnétiques Intenses, Grenoble, CNRS, UGA,

France 2Graduate School of Science and Technology, Niigata, Japan

3Department of Phyics, Niigata, Japan

Nous présentons des mesures de chaleurs spécifiques sur un monocristal d’excellente

qualité sous des champs magnétiques allant jusqu’à 27 T. La mesure à champ nul

au-dessus de la température de Néel, TN = 5.7 K, fait état d’une contribution électronique

modeste γ = 180 mJ/K². L’analyse de la dépendance en température dans l’état ordonné

révèle une contribution de magnons dont la relation de dispersion présente un gap, lié à

l’anisotropie du système. Cette analyse permet l’extraction de la contribution

électronique dans l’état ordonné, γ0 ≃ 5 mJ/K², dont la comparaison avec γ quantifie la basse dimensionnalité du système.

L’étude sous champ magnétique a permis d’établir avec précision le(s) diagramme(s) de phase magnétique en tenant compte de l’anisotropie du composé. Alors que l’application du champ selon l’axe c provoque une baisse monotone de la température d’ordre TN, celle selon l’axe a mets en évidence un maximum autour de 10 T précédant une chute similaire. L’extrapolation de ces dépendances en champ suggère l’existence de point critique quantique vers 50-60 T.



Enhancement of superconductivity near thelattice-coupled nematic quantum critical point

D. Labat1, I. Paul1

1Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris Diderot -Paris 7 & CNRS, UMR 7162, 75013 Paris, France

In the context of the Cu- and Fe-based high temperature superconductors(FeSC) theoretical studies1,2 have conjectured that the superconducting Tc in-creases significantly in the vicinity of a nematic quantum critical point (QCP).Such studies are based on electron-only models, that ignore coupling betweenthe electrons and the lattice strain that is invariably present. In this workwe study the effect of this coupling. The effective static electronic interactionbecomes gapped in all directions of the Brillouin zone with the exception twohigh-symmetry axes ; along any other direction, the noncritical elastic constantscutoff the nematic fluctuations3. This lattice-generated cutoff allows us to an-alyze the problem within BCS theory right up to the QCP. Making use of theBCS-like linear gap equation, we show that there is a crossover between a regimeof weak enhancement of the superconducting Tc, where the noncritical pairinginteraction is dominant, and a regime of strong enhancement dominated by thenematic pairing interaction, provided that the nemato-elastic energy scale issufficiently weak. These regimes are interpreted to cause the SC dome to beflat-shaped or peak-shaped, respectively. The former is the case for FeSC, whichexhibit strong nemato-elastic coupling.

1Lederer et al, PRL 114, 097001 (2015)

2Mishra et al, New J. Phys. 18, 103001 (2016)

3Paul et al, preprint at arXiv:1610.06168



Experimental charge and spin densities of the p-

O2NC6F4CNSSN radical using joint refinement method

Ariste Bolivard Voufack 1

, Nicolas Claiser 1

, Claude Lecomte 1

, Mohamed Souhassou 1

, Javier

Campo2 , Garry J. McIntyre

3 , Alwyn Bernard Dippenaar

4 and Delia A. Haynes

4

1CRM2, UMR 7036, CNRS-Université de Lorraine, BP 70239, Vandoeuvre-lès-Nancy, 54506,

France2Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Zaragoza 50009,

Spain

3Australian Centre for Neutron Scattering - Lucas Heights Campus New Illawarra Rd, Lucas

Heights NSW 2234, Australia

4Department of Chemistry and Polymer Science, Stellenbosch University, 7600 Stellenbosch,

Republic of South Africa

The p- O2NC6F4CNSSN radical carries one unpaired electron delocalized on the thiazolyl ring

and exhibits ferromagnetic order below 1.3 K (Luzon et al. (2010) ). To investigate the magnetic

interactions in the solid, high resolution X-ray and polarized neutron diffraction experiments have

been carried out. The spin resolved electron density is modelled using the MOLLYNX program

(Deutsch et al. (2012); Deutsch et al. (2014)), that allows simultaneous determination of both

charge and spin densities.

This communication will detail the methodology used and the analysis of spin and charge

densities and derived properties such as the electrostatic potential. Finally, the topology of the

electron density will characterize intra and intermolecular interactions, especially those involved

in magnetic pathways.

References

-Deutsch M., Gillon B., Claiser N., Gillet J.-M., Lecomte C. and Souhassou M., (2014), IUCrJ, 1,

194—199.

-Deutsch M., Claiser N., Pillet S., Chumakov Y., Becker P., Gillet J.-M., Gillon B., Lecomte C.

and Souhassou M., (2012), Acta Cryst. A, 68, 1—12.

-Luzon, J., Campo J., Palacio F., McIntyre, G. J., Rawson J. M., Less R. J., Pask C. M., Alberola

A., Farley R. D., Murphy D. M. and Goeta A. E. (2010), Phys. Rev. B 81, 144429.



Hematite/Ilmenite (FeTiO3)-(Fe2O3) superlattices by

PLD : new magnetic and transport properties

E. Popova 1, E. Chikoidze

1, J. Lion

1, F. Jomard

1, J. Vigneron

1, M. Fregnaux

2, A.

Etcheberry 2, N. Keller

1, and Y. Dumont

1

1GEMaC (Groupe d'Etudes de la Matière Condensée), Université de Versailles

Saint-Quentin en Y. & CNRS, Université Paris-Saclay, Versailles, France 2Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin en Y. &

CNRS, Université Paris-Saclay, Versailles, France

Development of materials that show both magnetic and semiconducting properties is

crucial for the realization of semiconductor-based spintronic devices. The solid

solutions between ilmenite (FeTiO3) and hematite (α-Fe2O3) have recently attracted

considerable attention due to their interesting magnetic and electronic properties that are

strongly dependent on ordering of cations as well as composition [1-3]. Ferrimagnetic

semiconductors arise when the arrangement of cations is ordered, whereas weak

frustrated disordered magnetism is observed for disordered cation distribution. The

Curie temperatures of ordered phases are higher than room temperature for

compositions between 50 mol.% and about 80 mol. % of FeTiO3. DFT calculations

have predicted a charge transfer at Fe2O3 and FeTiO3 interfaces in superlattices [6],

generated interface magnetism with “giant exchange-bias” [7]. Such effects have been

observed natural metamorphic mineral of nanocrystals.

By Pulsed Laser Deposition, artificial modulated composition hetero-structures

(Fe2-xTixO3-d/FeTiO3)n have been epitaxially deposited on α-Al2O3(0001) substrate,

varying the period thickness and the number of periods. Chemical composition has been

measured by SIMS and XPS profiles. Room temperature magnetic loops exhibit large

exchange bias (0.1 T) and stronger coercive field that single materials thin films.

Measured Curie temperature of magnetization is 325K. Transport properties of these

artificial superlattices have been investigated.

[1] H. Hojo, K. Fujita, K. Tanaka, et al., Appl. Phys. Lett. 89, 082509 (2006); ibidem 89,

142503 (2006)

[2] Hamie A., Popova E., Dumont Y., et al. Appl. Phys. Lett. 98, 232501 (2011)

[3] Bocher L., Popova E., Nolan M., et al. Phys. Rev. Lett. 111, 167202 (2013)

[4] R. Pentcheva and H. Sadat Nabi, Phys. Rev. B 77, 172405 (2008); H. Sadat Nabi, R.

J. Harrison, and R. Pentcheva, Phys. Rev. B 81, 214432 (2010)

[5] S. A. McEnroe, B. Carter-Stiglitz, R. H. Harrison, et al., Nature Nanotechnol. 2, 631

(2007)



Molecular Magnets: From the single molecule to the 3D self-assembly

D. Longo1, S. Royer1, C. Brun1, F. Debontridder1, P. David1, N.Witkowski1, T.Cren1 1 Institut des NanoSciences de Paris, Sorbonne Universités, CNRS UMR 7588 and UPMC, Paris, France

The presence of magnetic disorder in s-wave superconductors is able to reduce the

superconducting BCS gap and may ultimately destroy the coherence of the superconducting

state. A single magnetic impurity, presenting a large spin number, behaves classically and is

able to create a localized state within the BCS gap, known as Shiba state. A finite

concentration of classical magnetic impurities can form an impurity band from the

overlapping Shiba states, within the superconducting gap. The spatial decay of these bound

states critically depends on the dimensionality of the system, i.e. it is increased by reducing

the dimensionality [1]. Under some specific conditions, magnetic interaction between

several Shiba states in a either one-dimensional or two-dimensional array of magnetic

impurities on the surface of a superconductor may realize new topological phases [2].

One of the most remarkable examples of 2D superconductors is Pb/Si(111), since

superconductivity can arise in a single atomic plane of Pb [3,4]. In this poster, I will

summarize the results related to the surface characterization of this system and its complex

structural phases by means of LEED and STM measurements at room temperature.

Magnetic phthalocyanines (Pc) are very promising metal-organic molecules which can be

used as magnetic impurities when evaporated on a superconducting substrate [5]. Because

of the chemical flexibility of Pcs, their spin angular momentum can be tuned by simply

replacing the magnetic central atom, e.g. MnPc have s=5/2 whereas for the TbPc2 S=3.

Moreover, Pcs are known to form 2D self-assemblies on various metallic surfaces which

make possible to tailor two-dimensional ordered magnetic structures. Results about 2D self-

assembly of phthalocyanines on Pb/Si(111) in the sub-monolayer regime will be also shown.

[1] G. Ménard et al. Nature Physics 11, 1013 (2015)

[2] Braunecker, et al. Phys. Rev. Lett. 111, 147202 (2013)

[3] T. Zhang et al. Nature Physics 6, 104 (2010)

[4] C. Brun et al. Nature Physics 10, 444 (2014)

[5] Franke et al. Science 332, 940 (2011)



Nanocrystalline Nickel Synthesis by Pulsed Current

Amel Boukhouiete1, Zoubida Habes

2

1Laboratoire (LM2PM) Faculté des sciences, Université Badji-Mokhtar, Annaba, Algeria

2Université Badji-Mokhtar, 23 000 Annaba, Algeria

In this work, nickel deposits were produced using continuous and pulsed current

processes from watts bath. The optimum conditions of deposition were established and

the influence of pulse parameters, namely, pulse on-time, off-time and average current

density on the grain size, surface morphology and crystal orientation was determined.

The study showed that pulse current results in better properties of deposits and

significantly refined the crystal grain. The reduction of grains sizes has been found to

offer substantial grains in the properties of the deposited metal such as the hardness and

the corrosion resistance. Electrodeposition nickel has been investigated by Scanning

electron microscopy and X-ray diffraction



Nature de l'ordre orbital dans une perovskite

magnétique: nouvelle méthode multitechnique

Iurii Kibalin1,†

, Béatrice Gillon1, Arsen Gukasov

1, Alexandre Bataille

1,

Florence Porcher1, Ariste B. Voufack

2, Nicolas Claiser

2, Mohamed Souhassou

2,

Claude Lecomte2, Jean-Michel Gillet

3, Zeyin Yan

3, Masahisa Ito

4, H. Sakurai

4,

K. Suzuki4, Yoshiharu Sakurai

5, Christina Hoffmann

6, X. Wang

6

1 Laboratoire Léon Brillouin (CEA-CNRS), UMR12, CEA Saclay, France

2 CRM2, UMR7036, Université de Lorraine, Vandoeuvre-les-Nancy, France

3 Laboratoire SPMS, UMR8580, CentraleSupélec,Chatenay-Malabry, France

4 Gunma University, Kiryu 1-5-1, Gunma, Japan

5 Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo, Japan

6 Oak Ridge National Laboratory, Oak Ridge, USA † PNP NRC Kurchatov Institute, Gatchina, Russia

La pérovskite YTiO3 présente un ordre de spin ferromagnétique accompagné d’un ordre

orbital antiferro en dessous de 30K. Son étude détaillée a fait appel à toutes sortes de

techniques donnant des éclairages complémentaires sur ses propriétés électroniques.

L’approche que nous suivons vise à déterminer un seul modèle expérimental de densité

électronique sur la base conjointe de données provenant de différentes techniques,

diffraction de rayons X (magnétique ou non), diffraction de neutrons polarisés et

diffusion Compton (magnétique ou non) (Deutsch et al. IUCrJ (2014) 1,194–199). Nous

présentons plus particulièrement les mesures récentes effectuées par diffraction de

neutrons polarisés (PND) à 5K et 5T. Ces données sont analysées conjointement à celles

de diffraction magnétique de rayons X (Suzuki et al, Jpn J. Appl. Phys. (2009) 48,

056506) qui, comme la PND, donne accès à la distribution spatiale des électrons

responsables du magnétisme. L’affinement d’un modèle d’orbitales fournit ainsi une

information directe sur la nature des orbitales mises en jeu dans l’ordre magnétique et

orbital.

Densité d’aimantation dans YTiO3

obtenue par PND à 5K sous 5T,

reconstruite par la méthode du maximum

d’entropie (isosurface : 0.08 μB.A-3

)



Redox reactions induced by metals at the (100)and (111) surfaces of SrTiO3 probed by

secondary ion mass spectroscopy

Scola (Joseph)1, Jomard (Francois)1, Berini (Bruno)1, Dumont (Yves)1

1Groupe d’Etude de la Matiere Condensee, UMR 8635 du CNRS, UVSQ, 45avenue des Etats-Unis, 78035 Versailles Cedex

The deposition of a thin layer of aluminium has recently been shown to generatea 2D electron system at the surface of SrTiO3 thus being a simple and cost-efficient alternative to LaAlO3 deposition [1]. In the first atomic planes ofthe oxide, the oxygen is pumped by the Al film that oxidizes into insulatingAlOx. The properties of a 2D electron system obtained by this mean has beenextensively documented evidencing that oxygen vacancies are actually presentat the surface of the oxide [2,3].

We present here a direct investigation of the oxygen vacancy distribution belowthe surface of SrTiO3 substrates coated with a layer of Al or Au. High mass-resolution secondary ion mass spectroscopy has been proven to be an relevanttool to probe oxygen stoichiometry in oxides [4]. Here, the oxygen concentrationprofiles were compared depending on the coating metal. Experiments werecarried out on (100) and (111) oriented SrTiO3 surfaces. Oxygen vacancies areobserved in Al-coated SrTiO3 for both orientations but not in the Au-coatedsamples. An estimation of the oxygen vacancy concentration and their spatialextension below the surface is proposed.

[1] T. C. Rodel et al., Adv. Mater. 28, 19761980 (2016).

[2] T. C. Rodel et al. Phys. Rev. Appl. 1, 051002 (2014).

[3] S. McKeown Walker et al., Phys. Rev. Lett. 113, 177601 (2014).

[4] J. Scola et al. J. Phys. D: Appl. Phys., 50, 045302J (2017).



Revealing the complex band structure of

LaAlO3/SrTiO3 interface by high magnetic field

quantum transport

Ming Yang1, Kun Han

2, Ariando

2, Walter Escoffier

1 and Michel Goiran

1

1 Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), UPR 3228,

CNRS-UJF-UPS-INSA, 143 Avenue de Rangueil, 31400 Toulouse, France 2 Department of Physics and NUSNNI-Nanocore, National University of Singapore,

117411 Singapore

Email: [email protected]

Despite theoretical and experimental efforts realized in the past decade, the

intimate electronic properties of the two-dimensional electron gas at the LaAlO3/SrTiO3

(LAO/STO) interface remains an open question. The band-structure is complex since it

emerges from the 3d Ti3+/4+

atomic orbitals of the host STO material, with strong

electronic interactions. The electronic states are modulated by several parameters such as

the lattice distortion induced by the lattice mismatch between LAO and STO together

with the confining potential (which must be taken into account self-consistently). The

large Rashba spin-orbit coupling is another ingredient which comes into play.

Furthermore the spatial extension of the electronic gas and its actual dimensionality is as

well questioned.

o gain further knowledge on this long-standing issue, we performed

magneto-transport measurements on LAO/STO Hall bars at low temperature (500 mK)

under high magnetic field up to 70 T. A complex Shubnikov de-Haas oscillations pattern

appears in the longitudinal magneto-resistance RXX(B), which shows several frequencies

in the FFT (Fast Fourier Transform) spectrum.

The analysis of results suggests two distinct regimes under and above a threshold

magnetic field B~18T. We propose a model based on magnetic-field dependent

multi-subbands occupation. Nevertheless, the carrier densities deduced from the

frequencies of the SdH oscillations remain lower than the averaged carrier density

extracted from the Hall coefficient. This issue, together with a selective effect of the

back-gate voltage on RXX(B) and RXY(B), requires further experimental investigations .

Figure 1. RXX(B)and RXY(B)of

LAOSTO system under 70T magneticfield.



Search of new unconventionnal superconductors:

the case of Cr based compounds

Pierre Toulemonde1,2

, Justin Jeanneau1,2

, Manuel Nunez-Regueiro1,2

1Univ Grenoble Alpes, Inst. NEEL, F-38000 Grenoble, France

2CNRS, Inst NEEL, F-38000 Grenoble, France

After 30 years of research on the superconducting cuprates, the discovery of

high Tc superconductivity in related iron based pnictides in 2008 has stimulated the

search of new superconductors. In particular, antiferromagnetic (AFM) systems with 3d

transition elements, with high Néel temperature (TN), moderate magnetic moments and

with crystallographic 2D layers could be adequate parent phases for new

unconventional superconductors. Among 3d elements, Chromium has recently focused

attention with the discovery of superconductivity in CrAs at Tc2K under a moderate

pressure of 0.8GPa and in a family of Cr-based 1D compounds A2Cr3As3 (A=K,Rb,Cs)

with Tc values in the 2.2-6.1K range at ambient pressure.

During these last few years we have investigated several Cr-based systems like

CrSb2 and the layered Cr-based oxides, i.e. the Sr-based Ruddlesden-Popper (RP) series

Srn+1CrnO3n+1 obtained under high-pressure and high temperature (HP-HT) conditions.

We have used high pressure in order to tune and weaken the AFM order, to possibly

induce a superconducting state.

For CrSb2 we have followed the decrease of TN under pressure and found a

simultaneous structural and electronic transition, i.e. a transition from a semiconducting

state towards a metallic state, above 10 GPa. For the RP series, up to 20GPa no

superconductivity was found in n=1 (Sr2CrO4), n=2 Sr3Cr2O7 and n=∞ (SrCrO3)

members and the chromates remain insulating. Nevertheless we have evidenced several

interesting properties at ambient pressure in n=2 and 3 members. The antiferromagnetic

ordering of Sr3Cr2O7 at TN=210K, clearly visible in the magnetization and specific heat

measurements, yields a huge transition entropy, Rln(6). By neutron powder diffraction

(NPD) as a function of temperature we have determined the AFM structure, that

coincides with the one obtained from DFT calculations. It is accompanied by anomalous

asymmetric distortions of the CrO6 octahedra. Strong coupling and Lanczos calculations

on a derived Kugel-Khomskii Hamiltonian yield a simultaneous orbital and moment

ordering. Our results favor an exotic ordered phase of orbital singlets not originated by

frustration in this CrO2-bilayer system. Moreover in the case of Sr2CrO4, our NPD study

reveals that their CrO6 octahedra show an anomalous apparently inverse Jahn-Teller

effect, i.e. a smaller distortion at low temperature, i.e. below its TN=110K and TS=140K.

DFT calculations support this scenario.



Study of organic polluant degradation by advanced

processes

Zahia Benredjem1, Samia Saaidia

1, Karima Barbari

1, Abdelhak Djemel

1, Rachid delimi

1

1Laboratory of Water Treatment and valorization of industrial wastes. Badji Mokhtar University. Bp 12.

Annaba.23000. Algéria. [email protected]

The Advanced Oxidation Process (AOP) are promising environmentally friendly

technologies for the treatment of wastewater containing organic pollutants. The

objective of our work is to study the possibility of destroying the dye Methyl Orange by

some POA then compare the efficiencies of the processes used (Fenton, photo-Fenton

and electro-Fenton). Our study therefore focused on the degradation of this toxic dye.

The comparative study of Fenton, photo-Fenton and electro-Fenton processes revealed

that the electro-Fenton is the best method for oxidizing the dye. The dye of the

degradation kinetics by the electro-Fenton process is very fast where the degradation

rate reached 90.87% after 5 minutes. The degradation of organic matter was monitored

by UV / Visible spectrophotometry and its mineralization is valued by measuring the

chemical oxygen demand (COD). The influences of several parameters are studied.



Template synthesis and characterization of Bi2Te3 and

Sb2Te3 nanowires

Rashmi Rani, Travis Wade, Marcin Konczykowski

Laboratoire des Solides Irradies, Ecole Polytechnique, Palaiseau, France.

Topological insulators (TIs) are a new quantum state of matter which has gapless surface

states. Currently known TI materials can possibly be classified into two families, the HgTe

family and the Bi2Se3 family. It has been found that excellent thermoelectric materials can be

also topologically trivial. Bismuth, antimony and tellurium compounds (Bi/Sb/Te) are known

as the best thermoelectric materials for room temperature operation. However 2D quantum

matter is a challenge, due to the difficulty of separating surface contributions from the non-

conductivity of the bulk. Nanostructured synthesis/growth, doping, compositional tuning, or

band-gap engineering via device gating, has not yet completely suppressed bulk conduction

in the TIs.

Nano-scale topological insulators have a large surface-to-volume ratio that can manifest the

conductive surface states and are promising for devices. Electronic transport of

nanostructured TI’s exhibit novel quantum effects. The main obstacle for future

developement of TI based devices is growth of high quality TI structures.

Growth of nanowires with high surface to volume ratio can be realized by two methods,

chemical vapour transport and electro-deposition. The second method used in the presented

work and allows fabrication of structures such as p-n junctions, intercalation of magnetic or

superconducting dots.

We report the fabrication of high quality TI thermoelectric single crystal nanowire (Bi2Te3,

Sb2Te3) via electro-deposition (ED). The morphological structure of nanowires was studied

by SEM. Crystalline properties were investigated by TEM. Mono-crystal structure was

confirmed for all nanowires. ED growth parameters such as substrate, substrate annealing,

deposition potential and solution composition have been optimized for growth of mono

crystal nanowires of Bi2Te3 and Sb2Te3. Preliminary results show that electronic transport of

electrodeposited nanowires is dominated by surface states as testified by weak antilocaliation.

Keywords: Template synthesis, electro-deposition, nanowires.



Liste des participants

LASTNAME FIRSTNAME MAIL Nom du Laboratoire

ANDREEV Sergueï [email protected] Laboratoire Ondes et Matière d'Aquitaine

AUBAN-SENZIER Pascale [email protected] Laboratoire de Physique des Solides

BARRIER Nicolas [email protected] CRISMAT

BAUMARD Julie [email protected] Laboratoire Ondes et Matière d'Aquitaine

BELLEC Ewen [email protected] Laboratoire de Physique des Solides

BENREDJEM Zahia [email protected] Laboratoire de traitement des eaux et valorisation des déchets industriels

BERT Fabrice [email protected] Laboratoire de Physique des Solides

BIBES Manuel [email protected] Unité Mixte de Physique CNRS/Thales

BILGERI Tobias [email protected] Institut des Nanosciences de Paris (INSP)

BOBROFF Julien [email protected] Laboratoire de Physique des Solides

BRIÈRE Benjamin [email protected] GREMAN

BRUN Christophe [email protected] Institut des Nanosciences de Paris (INSP)

BURDIN Sébastien [email protected] Laboratoire Ondes et Matière d'Aquitaine

BUZDIN (BOUZDINE) Alexandre [email protected] Laboratoire Ondes et Matière d'Aquitaine

CANALS Benjamin [email protected] Institut Néel

CANO Andres [email protected] ICMCB

CARIO Laurent [email protected] Institut des Matériaux Jean Rouxel (IMN)

CARPENTIER David [email protected] Laboratoire de Physique

CAYSSOL Jerome [email protected] Laboratoire Ondes et Matière d'Aquitaine

CHABOUSSANT Gregory [email protected] Laboratoire Léon Brillouin

CHOGONDAHALLIMUNIRAJU

Naveen Kumar [email protected] Laboratoire National des Champs Magnétiques

Intenses

CIVELLI Marcello [email protected] Laboratoire de Physique des Solides

CLAISER Nicolas [email protected] Cristallographie, Résonance Magnétique et Modélisation

COLLET Eric [email protected] Institut de Physique de Rennes

CORRAZE Benoît [email protected] IMN

DARIE Céline [email protected] Institut Néel

D'ASTUTO Matteo [email protected] Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC, umr7590)

DE BRION Sophie [email protected] Institut Néel

DE' MEDICI Luca [email protected] LPEM

DE MUER Albin [email protected] Laboratoire National des Champs Magnétiques Intenses

DEMOURGUES Alain [email protected] ICMCB

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DUC Fabienne [email protected] Laboratoire National des Champs Magnétiques Intenses

DUMONT Yves [email protected] GEMaC

FAURE Quentin [email protected] INAC - CEA Grenoble / Institut Néel - CNRS

FOERSTER Dietrich [email protected] Laboratoire Ondes et Matière d'Aquitaine

FOURY Pascale [email protected] Laboratoire de Physique des Solides

GILLON Beatrice [email protected] Laboratoire Léon Brillouin

GOIRAN Michel [email protected] LNCMI-T

GONZALEZ VALLEJO Isabel [email protected] Laboratoire de Physique des Solides

GUIGNARD Marie [email protected] ICMCB

HARDY Vincent [email protected] CRISMAT

HORVATIC Mladen [email protected] Laboratoire National des Champs Magnétiques Intenses

ILAKOVAC Vita [email protected] Laboratoire de Chimie Physique - Matière et Rayonnement

JANOD Etienne [email protected] Institut des Matériaux Jean Rouxel (IMN)

JAUBERT Ludovic D.C. [email protected] Laboratoire Ondes et Matière d'Aquitaine

KNAFO William [email protected] Laboratoire National des Champs Magnétiques Intenses

KONCZYKOWSKI Marcin [email protected] Laboratoire des Solides Irradies

LABAT Dimitri [email protected] Matériaux et Phénomènes Quantiques

LACROIX Claudine [email protected] Institut Néel

LAFLORENCIE Nicolas [email protected] Laboratoire de Physique Théorique

LAKEHAL Massil [email protected] Matériaux et Phénomènes Quantiques

LE BOLLOC'H David [email protected] Laboratoire de Physique des Solides

LEPETIT Marie-Bernadette

[email protected] Institut Néel

LERIDON Brigitte [email protected] LPEM

LONGO Danilo [email protected] Institut des Nanosciences de Paris (INSP)

LOUAT Alex [email protected] Laboratoire de Physique des Solides

MAGLIONE Mario [email protected] ICMCB

MARIOTTO Marie-France [email protected] Laboratoire de Physique des Solides

MÉASSON Marie-Aude [email protected] Institut Néel

MESSIO Laura [email protected] LPTMC

MIREBEAU Isabelle [email protected] Laboratoire Léon Brillouin

MORICE Corentin [email protected] Institut de Physique Théorique

PAUTRAT Alain [email protected] CRISMAT

PENG Wei [email protected] Laboratoire de Physique des Solides

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PEPIN Catherine [email protected] Institut de Physique Théorique

POILBLANC Didier [email protected] Laboratoire de Physique Théorique

POUCHARD Michel [email protected] ICMCB

POURRET Alexandre [email protected] INAC/PHELIQS

RABA Matthias [email protected] Laboratoire National des Champs Magnétiques Intenses

RANI Rashmi [email protected] LSI

RAVY Sylvain [email protected] Laboratoire de Physique des Solides

ROBERT Julien [email protected] Institut Néel

RODIÈRE Pierre [email protected] Institut Néel

RUEFF Jean-Pascal [email protected] Synchrotron SOLEIL

SAKLY Nahed [email protected] Laboratoire Ondes et Matière d'Aquitaine

SANTOS-COTTIN David [email protected] LPEM

SCOLA Joseph [email protected] GEMaC

SERRIER-GARCIA BRINON Lise [email protected] Laboratoire de Physique des Solides

SHEIKIN Ilya [email protected] Laboratoire National des Champs Magnétiques Intenses

SIMONET Virginie [email protected] Institut Néel

STERPETTI Edoardo [email protected] IMPMC

SUCHOMEL Matthew [email protected] ICMCB

TA PHUOC Vinh [email protected] GREMAN

TENCE Sophie [email protected] ICMCB

TOULEMONDE Pierre [email protected] Institut Néel

VERSEILS Marine [email protected] IMPMC

VIART Nathalie [email protected] Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)

VIGNOLLE Baptiste [email protected] ICMCB

VILLAIN Jacques [email protected] Académie des Sciences, ILL

VOUFACK Ariste [email protected]

Cristallographie, Résonance Magnétique et Modélisation

WADE Travis [email protected] Laboratoire des Solides Irradies

YANG Ming [email protected] Laboratoire National des Champs Magnétiques Intenses

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Mardi 28 mars Introduction

Session Supraconductivité I Colloque - Emerging symmetries and the pseudo-gap state of the cuprates – C. Pépin Evidence for hidden fermions and unconventional pairing in high-temperature superconducting cuprates – M. Civelli Evolution of spectral functions and transport quantities with doping in the SU(2) theory of cuprates. - C. Morice

Pause Focus - Fermi surface instabilities in ferromagnetic superconductors – A. Pourret Les cuprates à haute Tc, voix de chimistes – M. Pouchard

Session matériaux Colloque - Stabilizing several anions (F, O, OH, S) close to transition metals or RE to tune the optoelectronic properties of new materials – A. Demourgues

Poster

Mercredi 29 mars Colloque spécial Transitions et phases

topologiques Colloque - Quelques propriétés extraordinaires de la physique à deux dimensions – J. Villain

Session Magnétisme I Colloque - Frustration, chirality, multiferroism – V. Simonet Interplay between charge transfer and magnetic transition in the quadruple perovskite (YMn3)Mn4O12 – M. Verseils Field-induced quasiparticles driving the quantum phase transition in Ising-like antiferromagnetic spin chain – Q. Faure

Pause Focus - Deux articles intéressants – M. Maglione Pressure induced multiferrocity in PrMn2O5 – W. Peng Chiral spin liquid on kagome antiferromagnet induced by Dzyaloshinskii-Moriya interaction – L. Messio Emergent phenomena in spin liquids – L. D.C. Jaubert

Déjeuner Session techniques avancées

Colloque - Techniques spectroscopiques avancées pour l'étude des systèmes corrélés. – J.-P. Rueff Focus - Sonder et impacter les matériaux aux échelles de temps ultra-rapides – E. Collet Time-resolved X-ray Diffraction on Density-Waves systems – S. RAVY

Collective transport of charges in charge density wave sytem based on traveling soliton lattices – E. Bellec

Three-dimensional critical phase diagram of a heavy-fermion Ising antiferromagnet – W. Knafo

Pause Session nouveaux matériaux

Focus - Multiferroics: What now? – N. Viart AMnGe2O6 (A = Ca or Sr) : effet de la nature du cation divalent dans la structure pyroxène – C. Darie Rb2Ti2O5: quand un diélectrique n'est pas un isolant... – B. Leridon Toward a gated FET on the basis of spin-transition polymers – S. Andreev Présentation de l'Ecole du GDR 2018 - D'Astuto M.

Poster

Jeudi 30 mars Session Magnétisme II

Colloque - Etats magnétiques exotiques engendrés par frustration – F. BERT Focus - Systèmes artificiels, systèmes modèles – B.CANALS Défauts topologiques dans les verres de spin reentrants – I.Mirebeau Double vibronic process in the quantum spin ice candidate Tb2Ti2O7 revealed by terahertz spectroscopy – S.DE BRION

Pause Focus - Highly Efficient and Tuneable Spin-to-Charge Conversion at LaAlO3/SrTiO3 Interfaces Through the Inverse Rashba-Edlestein Effect – M. Bibes Fragmentation de spins par un champ magnétique alterné dans le composé Ho2Ir2O7 – J. ROBERT Comportements de "chaîne-aimant" et "molécule-aimant" dans des oxydes à chaînes de spins – V. Hardy, CRISMAT NMR of the putative Bose-glass regime in the doped DTN at high H unveils the existence of a new, impurity-induced BEC-type phase – M. Horvatic Doped DTN at high fields – Theoretical surprise – N. Laflorencie

Déjeuner Session Supraconductivité II

Focus - Evidences of orbital-selective correlations in the measured gap structure in FeSe – L. de' Medici Superconductivity in the iron-based hydride LaFeSiH – S. Tencé Détermination du paramètre d'ordre supraconducteur de FeSe à partir de mesures thermodynamiques, magnétiques et spectroscopiques – P. Rodière Tuning of the phase diagram and quantum critical point by disordered in Fe-based superconductors – M. Konczykowski

Pause Stick-slip Phenomena and Memory Effects in Moving Vortex Matter – L. Serrier-Garcia Brinon Two-dimensional topological superconductivity in Pb/Co/Si(111) – C. Brun Electrostatic modulation of superconductivity in few nm BSCCO-2212 films – E.Sterpetti Quantum criticality, superconductivity and Fermi surface dimensionality: CeIn3, CeRhIn5, and CePt2In7 – I. Sheikin

Session vulgarisation Vulgariser la matière condensée : pourquoi ? comment ? – J. Bobroff Sessions parallèles : Poster, Atelier vulgarisation, Visite Aérocampus

Vendredi 31 mars Session Phénomènes émergents, corrélations, et dynamique

Colloque - Kondo effect: an old problem, some new aspects – C. Lacroix Focus - Electric field induced Insulator to Metal Transition in Mott insulators – B. Corraze Transition Isolant de Mott-Métal dans Sr2IrO4 – A. Louat Probing the metal-insulator transition of BaCo 1-x Ni x S 2 by optical conductivity – D. Santos-Cottin

Pause Transition isolant métal induite par pression dans l'isolant de Mott moléculaire organique [Au(Et-thiazdt)2]. - Benjamin Brière Instabilités structurales et électroniques des bronzes phosphates de tungstène – A. Pautrat, Determination of the magnetic structure of CePt2In7 by means of neutron diffraction – M. Raba Neutron diffraction study of CeRh2Si2 under pulsed magnetic field – N. Kumar Chogondahalli Muniraju e---phonon coupling in a molecular crystal Kappa-(BEDT-TTF)2Cu2(CN)3 measured by Resonant Inelastic X-ray Scattering – V. Ilakovac

Déjeuner

Réunion plénière du GDR 3732 «...

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