Oxydes de métaux de transition: réseaux carrés et triangulaires

pour générer de nouvelles fonctionnalités

Laboratoire CRISMATCRIstallographie

et Sciences des MATériaux

Unité

Mixte de Recherche n°6508 CNRS/ENSICAEN

Antoine Maignan

Collége

de France, Chaire de Physique de la Matière CondenséeAntoine Georges, Cours 6: transition métal-isolant de Mott

dans

les oxydes de métaux de transition

Why

are we

interested

in oxides

?plenty

of cation combinations

(playground

for Chemists)

natural

abundancegreen materials

«

air prepared

»

(Pb free etc…)

applications: microelectronics: dielectrics

(HfSiO2

) , ferroelectrics(SrBi2

Ta2

O9

),

QTM quantum computing

(Ca3

Co2

O6

) ?

energy: (TCOs

for PV ITO, Li-batteries Lix

CoO2

, SOFC H2(La,Sr)(Co,Fe)O3-d

, catalysis

nanomaterials

to replace PtRh, superconductivity

YBa2

Cu3

O7

, thermoelectricity

?)

FeRam TEG

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

Introduction

Perovskite: very

rich

system!Structures and properties!!

T (K)0 50 100 150 200 250

ρ (Ω

.cm

)

10-2

10-1

100

101

M (µ

B)

0

1

2

3

4

RB

=0/R

B=5

T

ρ (Ω

. cm

)

T (K)

0

5T

0 50 100 150 200 25010-2

10-1

100

101

102

50

100

150

200

CMRStrong

coupling

between

structures,transport

and magnetism.

ABO3

A-site (Ln, A)

O

B-site (Mn)

Perovskite

structure

Flexibility

of the structure with

regard to cationic

and

anionic

replacements and tolerance

to ion defects.

aP

ABO3

AO and BO frameworks

Spin-Charge-Orbital coupling

Ln

3+x Ca 2+

1-x Mn

3+1-x Mn

4+

x O3Ln

3+x Ca 2+

1-x Mn

3+1-x Mn

4+

x O3

Square-shaped window

Tilting

Diamond-shaped window

No tiltingNo tilting

Distortiont > 1 → hexat = 1 → cubict < 0.96

→ orthorhombic

…)(2),(

OMn

OALn

rrrr

t+

+=

Tolerance factorGoldschmidt

factor

-

manganese valency

(Mn3+/Mn4+)-

average A-site cationic radius (<rA

>)

Ln

3+x Ca 2+

1-x Mn

3+1-x Mn

4+

x O3

(Ln,A)-O and Mn-O interatomic

distances

AO / BO frameworks

if O3 !!

Fixed

Mn valence

Ln0.7

A0.3

MnO3

Fixed

<rA

> = 1.255 Å

#Nd0.7

Ba0.3

MnO3

propertiesTh0.35

(Bax

Sry

Caz

)MnO3

A-site disorderσ2

= Σyi

ri2-<rA

>2

x ( P r1 - x

C ax

M n O3

)

0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 00 .

0 . 5

PrMnO3

. 0

1 . 5

2 . 0

2 . 5

3 . 0

3 . 5

1 5 0

2 0 0

2 5 0

3 0 0

TC

M4K

(μB

/ mol

. Mn)

T(K

)

TN

CMR CMR

FMI

CO

AFM

I

CG

TN

TCO

CaMnO3

100

50

0

Manganites : Complex

magnetic

and electronic

phase diagram

Magnetic

properties

: magnetization, susceptibility….

… Correlated

withtransport properties 0.95

0.85

0.925

0.975

Sm1-xCaxMnO3

0 50 100 150 200 250 3000.0

0.2

0.4

0.6

0.8

1.0

1.2

0.87

0.80M (µ

B/f.u.

)

0.83

0.75

T (K)

J. Solid State Chem. 134, 1, 198 (1997)

Phys. Rev. B 60, 14057 (1999)

0 50 100 150 200 250 3000.005

0.010

0.015

0.020

0.8

1.0

1.2

1.4

1.6

1.8

0

7T

0 50 100 150 200 250 30010-4

10-3

10-2

10-1

100

101

102

103

100

101

102

103

104

105

0

7T

0 50 100 150 200 250 30010-4

10-3

10-2

10-1

100

101

102

103

104

105

0

2

4

6

0

ρ 0/ρ

7T

7T

x = 0.90

x = 0.85x = 0.80

x=0.07

x=0.10

x=0.12

0 50 100 150 200 250 300 350 400

0.005

0.010

0.015

0.020

χ' (e

mu.

fu-1

)

f=100Hzhac=3 Oe

T(K)

0 50 100 150 200 250 300 350 4010-1

101

103

105

107

109

Elec

tric

al r

esis

tivity

(m

Ωcm

)

T (K)

0.10

0.08

0.07

0.12 0.15

CaMn1-x

Mox

O3

Ex1Impurity

induced

CO

20 29 38 47 56 65 74 83 92 101

-1000

6000

13000

20000

27000

34000

41000

48000

55000

62000

2 Theta (deg.)

Inten

sity (

a.u.)

101

020

200

121

002

201

102

211

112

031Pnma

P21/m

1.5K

305K

201,

102

101

020

101,

020

200,

-121

,002

-201

,-102

-211

,-112

-101 12

1

211 ,

130,

031,

112

220,

022

TN

TOO

CaMn0.9

Mo0.1

O3magnetism

[TN

]and

structure [TOO

] vs.

T

ND-LLB-G4 1 f (T)

Ex1

a b002

002

200

CaMn0.9

Mo0.1

O3ME f(T)

DE 300K 90K image

0 50 100 150 200 250 300 350 40010-1

101

103

105

107

109

Elec

tric

al r

esis

tivity

(m

Ωcm

)

T (K)0 50 100 150 200 250 300 350

-350

-300

-250

-200

-150

-100

-50

0

50

100

Ther

moe

lect

ric p

ower

(μV

K-1)

T (K)

Propriétés

physiques f(T)

T (K)0 50 100 150 200 250 300

M ( μ

B/f.

u.)

0.010

0.012

0.014

0.016

0.018

0.020

0.022

0.024

0.026

Pnma P21

/m

Ex1

CaMn1-x

Mox

O3

Ex1

Charge and orbital Ordering

e.g. Pr0.5

Ca0.5

MnO3

Mn3+ Mn4+Insulating

Antiferromagnet

Metallic

Ferromagnet

H > 25 T

M (μ

B/f.

u)

0 20000 40000 60000 800000,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

T=2.5K

3

2

1

H (Oe)

Pr0.5

Ca0.47

Ba0.03

MnO3

Manganites : successive M(H) at

2.5 K, T= 300K

The ferromagnetic

fractiondecreases

with

the number

of

thermal cycling

: history

effect

μ0H(T)

3

2

1

T=2.5K

0 1 2 3 4 50

1

2

3

4M

(μB/f.

u) Pr0.6

Ca0.4

Mn0.99

Cr0.01

O3

μ0H(T)0 1 2 3 4 5

0

1

2

3

4

32

1

T=2.5 K

M (μ

B/f.

u)Pr0.6

Ca0.4

Mn0.98

Ga0.02

O3

μ0 H(T)0 1 2 3 4 5

0

1

2

3

4

31

T=2.5 K

M (μ

B/f.

u)

Pr0.6

Ca0.4

Mn0.96

Ga0.04

O3

Characteristic

H of the steps

:irreproducibility

3.2 3.4 3.6 3.8 4.0 4.2 4.4

2.4

2.6

2.8

3.0

3.2

T = 1.5 K

M (μ

Β / f.u

.)

μ0Η(Τ)

At even lower T, additional steps : no characteristic scalesas expected in MT like transition

Influence of the temperature

Avalanches

Magnetization Steps

No “critical fields”

strictly speakingNo specific magnetization values associated with the plateaus

Stepwise growth of the FM phase at the expense of the AFCOO phase ?

AFC00

FM Hintermediate

states

Ex4’Phase separation

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

LBaCo2

O5.5

123

112

Oxygen

and cation ordering: ordered

perovskite

TMI

=300K

210 50 100 150 200 250 300 350 400

10-3

10-2

10-1

100

101

102

103

104

105

T(K)

ρ(Ω

.cm

)

HoBaCo2

O5.5

LnBaCo2

O5+x

: x=0.5, pure trivalent cobalt, TMI

=f(rA

)trivalent Ho and Y same ionic radius (0.1072 and 0.1075nm)

Hole

vs Electron asymmetry

0T

0 50 100 150 200 250 300

0

50

100

150

7T

0T

S( μ

V.K

-1)

T(K)

0 50 100 150 200 250 300

0

50

100

150

200

TEP sign change at TMI

from metal S = -2 μV.K-1

(e-) to insulator S>>0 (h+)

Possible spin blockade in 112High T : an eg

electron Co2+

can movein a background of IS/HS Co3+

Broad eg

band , S<0 and small abs. value

Low T : an eg

electron Co2+

cannot move in a background of LS Co3+

, requires to flip other spins, wrong spin-states LS Co2+ and IS Co3+

instead of LS

Low T : a tg

hole Co4+

can hopin a background of LS Co3+

, Localization of heavy holes as T decreases, S>>0

A. Maignan et al, Phys. Rev. Lett. 93, 026401 (2004)

« Co3+

»

-

112 cobaltites

CuO

tenorite

oxidespiral induced electric polarization in the 213K-230K range

where an incommensurate antiferromagnetic

structure is observedC2/c monoclinic

structure (distorted

NaCl

struct.)

c c

Y

BaO (Fe,Cu)O2

a b FeO2

CuO2

112-

YBaCuFeO5

ordered

perovskite

(Y/BaO), isostructural

to YBaCo2

O5

Do Fe and Cu order

?

P4/mmm P4mm

Kundys B et al., APPLIED PHYSICS LETTERS 94 , 072506 2009

0 50 100 150 200 250 300

0.0

0.1

0.2

0.3

0.4

0

20

40

60

80

100

120

1407.6

7.8

8.0

8.2

8.4

8.6

0

200

400

600

(c)

Cur

rent

(pA/

cm2 )

Pola

rizat

ion(

ΔP(µ

C/c

m2 ))

T(K)

(b)100kHz

10kHz

5kHz

ε'

(a)

H = 0.3 Tχ

(em

u.g-1

)*10

6

YBaCuFeO5

TN2

Magnetoelectric

coupling

Incommen.Antiferro.

CommensurateAntiferromagnet

Paramagnetic

Complex

IncommensurateAF structure

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

3 Co(2) : kagomé

1 Co(1) : triangular

LnBaCo4

O7

vCo

= 2.25 3Co2+

: 1Co3+

Charge ordering ?

Network ofCoO4

tetrahedra

kagome

Co cations: 2 frustrated

magnetic

networks

kagome pyrochlore

YbBaCo4

O7

and YbBaCo4

O8

100 150 200 250 3006.255

6.260

6.265

6.270

6.275

a (Å

)

T (K)

Space

group P63

mc , a ≈

0.63 nm, c ≈

1.03 nm

TS

100 150 200 250 300 350120

140

160

180

200

220

240

260

Y3+Yb3+

0.5Y3+

0.5Yb3+

Y3+

Yb3+0.5Y

3+0.5

Yb3+

rL3+(nm)

T S(K

)

S(μV

/K)

T(K)

0.0860.0870.0880.0890.090160180200220240260280300320

LBaCo4

O7

: ionic

radius of L3+

controls

TS

0 50 100 150 200 250 300 350

1x104

2x104

3x104

4x104

ParamagnetismAF fluctuations

shortrangeAF

AF

TN

TSP31cPbn21

χ-1 (g

.em

u-1)

T (K)

YbBaCo4

O7

: from

geometric

frustation

to long–range

AF

Geometric

frustration lift by a first-order

structural transition

Formula sum CaBaCo4 O7

Formula weight 525.134

g/mol

Crystal system orthorhombic

Space group P b n 21 (33)

Cell parameters a=6.2872(2)

Å

b=11.0043(3)

Å

c=10.1913(2)

Å

Cell volume 705.10(3)

Å3

Calc. density 1.23664

g/cm3

Atom x y z

Ca 1/2 1/2 1/2 4b

Ba 1/4 3/4 3/4 4c

Co1 0 0.1209 0.1209 16e

O1 0 0 3/4 24f

O2 1/4 1/4 3/4 4d

CaBaCo4

O7

Distortion

CaBaCo4

O7 Ferrimagnetic

0 50 1000,0

5,0x10-31,0x10-21,5x10-22,0x10-22,5x10-23,0x10-23,5x10-24,0x10-24,5x10-25,0x10-25,5x10-26,0x10-2

40 50 60 70 80

0,05,0x10-3

1,0x10-2

1,5x10-2

2,0x10-2

2,5x10-2

3,0x10-2

3,5x10-2

4,0x10-2

4,5x10-2

5,0x10-2

χ (e

mu.

g-1)

T (K)

0,003 0,004 0,005 0,006 0,007101

102

103

104

105

106

ρ (Ω

.cm

)

T-1 (K)

zfc fcc fcw

χ (e

mu.

g-1)

T (K)

0 10 20 30 40 50 60 70 80 90 100

10

12

14

16

18

20

22

24

26V517, Bias Field 1V, 1K/min

ε'

T(K)

5kHz (1K/min) 10kHz (1K/min) 50kHz (1K/min) 100kHz (1K/min)

0 10 20 30 40 50 60 70 80 90

10

12

14

Ferrimagnetic

114

0 10 20 30 40 50 60 70 80 90

-80

-60

-40

-20

0

20

40

60

80

P(μ

C/m

2 )

T(K)

+111kV/m -111kV/m

TC

TC

Spin induced

ferroelectric

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

hexagonal perovskiteABO3

A=Ba

Ba

Hexagonal close packed

stacking

of the AO3

layersEvery

AO3

unit, one octahedron

is

created, occupiedby Co4+

Hexagonal Perovskites2H-BaCo4+O3 : a 1D compound with

edge-shared

CoO6

octahedra

The chains

of CoO6

octahedra

forma triangular

array

M. Parraset al, J. Solid State Chem. 120 , 327 (1995)

Alternating

hexagonal (h) and cubic

(c) stackingof the AO3-δ

layers

(hhhccc) yields

the 12-HCreation

of CoO4

tetrahedra

3D array

of CoOn

polyhedra

12H-Ba0.9

Co+3.2O2.6 : units

of edge-shared

CoO6

octahedra

bridgedby CoO4

tetrahedra

A.J. Jacobson et J.L. Hutchison, J. Solid State Chem. 35, 334 (1980)K. Boulahya et al , Phys. Rev. B 71, 144402 (1999)

12H-Ba0.9

Co+3.2O2.6 : structure

Transmission electronmicroscopy

: hhhccc

EDS coupled

to ED :Ba/Co = 0.9 ratio

X-ray diffraction :12H, P63/mmca=0.56612 (1) nmc=2.84627 (8) nm

A. Maignan et al , J. of Solid State Chem. 179 (2006), in press

A3n+3m

A’n

B3m+n

O9m+6n

: intergrowth

of n[A3

O9

] and m[A3

A’O6

] triple layersCreates

B octahedral

sites and trigonal prism

sites (A’)

For A’=B=Co and n=1, m=0 Ca3 Co2 O6

1:1 CoO6

trigonal prism

and octahedron

Geometric

frustration : hexagonal

a = b = 9.13 Å

c = 10.58 Åinterchain

distance : 5.24 Å

intrachain

distance : 2.6 Åspace group R3 cK.E. Stitzer et al, Curr. Opin. Solid State Mater. Sci. 5, 535 (2001)

H. Fjellvag et al , J. Solid State Chem. 124, 10 (1996)

0 50 100 150 200 250 300 350 4000,0

5,0x10-3

1,0x10-2

1,5x10-2

TC

0.3 Tzfc

SrCoO3

χ (e

mu.

g-1)

T (K)

SrCoO3

: edge-shared

Co4+O6

octahedrain the Pm3m cubic

perovskite

(a=0.3836 nm)Ferromagnet

with

TC = 280 K , Co4+-O-Co4+

180°

exchange

P. Bezdicka et al, Z. Anorg. Allg. Chem. 619, 7 (1993)

SrCoO3

: edge-shared

Co4+O6

octahedrain the Pm3m cubic

perovskite

-6 -4 -2 0 2 4 6-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

1,5

2,0

T = 2 K

SrCoO3

M (µ

B/f.u

.)

μ0H(T)

Conventional

ferromagnet

MS

= 1.75 μB

/Co

Co4+

is

neither

100%

LS or HS

0 50 100 150 200 250 300 350

0,02

0,04

0,06

0,08

0,10

0,12

0,14

ZFC

FC 0.3 T2H-BaCoO3

χ

(em

u.m

ol-1)

T (K)

2H-BaCo+4O3 : weak

ferromagnetism

below

TC

= 50 K ?effect

of the 1D character

of the Co-O array

00,0

0 100 200 3000,0

0,2

0,4

0,6

0,8

1,0

1,2

TC

µ0h

ac = 10-3 T

χ'' (

emu/

mol

)

T (K)

12H-Ba0.9

Co+3.2O2.6 : ferromagnetism

below

TC

= 50 K

0 50 100 150 200 250 300 3500

1

2

zfc

fc 12H-BaCoO3-δ

χ (e

mu.

mol

-1)

T (K)

Magnetic

susceptibility

values 10 times larger

than

in the 2H

1,0

1,5

2,0

2,5

3,0

0 100 200 300 400100

101

102

103

104

105

106

ρ (Ω

.cm

)

(7T)(0T)

T (K)

ρ H=0

T / ρ

H=7

T

0 2 4 6 8-60

-50

-40

-30

-20

-10

0

100 K

% M

R 40 K

200 K

75 K

125 K

50 K

μ0H (T)

12H-Ba0.9

Co+3.2O2.6 : negative

magnetoresistance

at

TC

= 50 K

Bump

in the ρ(T) curve

at

TC -60% at

50K in 7 T

No MR measured

in the 2H : related

to the ferromagnetism

of the 12H

spin/charge interplay

Large H dependence

at

TC

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

-0,15

-0,10

-0,05

0,00

0,05

0,10

0,15 2H - BaCoO3

T = 20 K

T = 50 K

T = 2.5 K

T = 10 KT = 5 K

M (μ

B/f.u

.)

µ0H (T)

-6 -4 -2 0 2 4 6-6

-4

-2

0

2

4

6

μ0H(T)

T = 2 K

M (e

mu.

g-1)

2H-BaCo+4O3 : weak

ferromagnetismbelow

TC

= 50 K ?

M5T

= 0.15 mB

/Co at 2.5 K μo

Hc

~ 0.8T at 2.5 K

At

2K no special

change

-6 -4 -2 0 2 4 6

-30

-20

-10

0

10

20

30 T = 2 K

M (e

mu.

g-1)

μ0(T)

12H-Ba0.9

Co+3.2O2.6 : ferromagnetismbelow

TC

= 50 K

-6 -4 -2 0 2 4 6-1,2-1,0-0,8-0,6-0,4-0,20,00,20,40,60,81,01,2

10 K

5 K2.5 K

50 K

M (µ

B/f.u

.)

µ0H (T)

M5T

= 1.2 μB

/Co and μ0

Hc

~ 1T at 2.5 K

At

2K, additional

M jumps

Similar

to the 5H

-6 -4 -2 0 2 4 6

-30

-20

-10

0

10

20

30

H = 250 Oe / sec

H = 10 Oe / sec

H = 110 Oe / sec

T = 2 K

M (e

mu.

g-1)

μ0H(T)

12H-Ba0.9

Co+3.2O2.6 : M jumps

at

2 K

Varying

the H sweep

rate or the waiting

timedoes

not suppress

the steps

0,0 0,5 1,0 1,5 2,0 2,50

5

10

15

20

/0.1T 60 sec

/0.25T 60 sec

T = 2 K

M (e

mu.

g-1)

μ0H(T)

χ(a.

u.)

TC2

TC1

T(K)0 10 20 30 40 50 60 70

0,0

0,1

0,2

0,3

0,4

0,5

0,6

10-3T

Ca3

Co2

O6 single crystals

A. Maignan et al., EPJB 15, 657 (2000)

TN

TB

fc

zfc

0 5 10 15 20 25

0 5 10 15 20 25

0.000

0.002

0.004

0.006

0.008

χ''(e

mu.

g-1)

hac=3 OeCa3Co2O6 (crystal, H//chains)

104

103

102101

10-1

100

10-2Hz

T(K)For f>1 Hz, T(χ’’max

) increasesas in a superparamagnet

But f <1Hz, fixed T(χ’’max

)

1 cmA3n+3m

A’n

B3m+n

O9m+6n

: A’=B=Co and n=1, m=0 Ca3 Co2 O6

MagnetismCa3

Co2

O6

c

J > 0

Ferro IntrachainCoupling

AntiFerro

Interchain

CouplingJ’ < 0

“

1 D + Frustration “

c

+

_

?

intrachain

: ferro

(F)interchain

: antiferro

(AF)

TN

= 25K

S = 0 → Octahedron S = 2 → Trigonal

Prism

Co3+

Decrease of the AF peak intensity below ∼

15K !Loss of the magnetic coherence along the chain ?

isolated finite spin units ?S. Aasland et al, Solid State Comm. 1997, 101, 197.

Strong

local anisotropy

(TP)

XMCD on crystals

: TP S=2, Oct. S=0large orbital moment 1.7 μB

Consistent with

the special

crystal

field

splittingin the Trig. Prism

: orbital d2

Predicts

large orbital moment :exp. Ms (10K) > 4 μB

Responsible

for the strong

magnetic

anisotropyL. H. Tjeng et al, Köln University

0 1 2 3 4 5 6 7 8 90

1

2

3

4

5

T = 2 K

M (μ

Β /

f.u.)

μ0H(T)

0 1 2 3 4 5 6 7

0.1

1

10 T = 2 K1.2 T

2.4 T3.6 T

7.1 T5.9 T

4.7 T

dM/d

H (a

.u.)

μ0Η(Τ)

c H

A. Maignan et al, J. of Mater. Chem. 14, 1231(2004)

Ca3

Co2

O6

QTM

n=1, m=0

Ca3

Co2

O6

–

magnetization stepsIsing triangular TN

=24K

0 1 2 3 4 5 60

1

2

3

4

5

T=10K

M (μ

B/f.u

.)

μ0H(T) 0 2 4 6 8 100

1

2

3

4

5

T=2K

M (μ

B/f.u

.)

μ0H(T)

ΔH=3.6T

ΔH=1.2TFI →

FO

0 25 50 75 100 125 150 175 2000

2

4

6

8

10

12 TN

CM (J

K -1

mol

-1)

T(K)

Ca3

Co2

O6

–magnetodielectric coupling

0 1 2 3 4 5 60

1

2

3

4

5

M (μ

B/f.u

.)

0 1 2 3 4 5 6

-1

0

Δε H

/εsa

t (%

)

μ0H(T)

T=10K

0 1 2 3 4 5 6-3

-2

-1

0

ΔεH/ε

sat(%

)

μ0H(T)

T=4K

0

1

2

3

4

5

M (μ

B/f.u

.)

0 1 2 3 4 5 60.00.20.40.60.81.01.2

χ(μ B/T

·f.u.

)

0 0

0.5

1.0

1.5

χ(μ B/

T·f.u

.)

Δε∼-χBellido N, Simon C, Maignan A. , Phys. Rev. B 77, 054430 (2008)

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

2 ceramic

substrates

that

serve as thermal link

and electrical

insulation

of p-type and n-type diceDices

connected

electrically

in series

and thermally

in parallelSolder at

the connection

joints to ensure

the electrical

connections and hold

the module together

How a TE Generator

Works ?

Figure of merit

Power factor

ρκ=

2SZ

ρ=

2SPF

For applications : n and p type materials

withZT > 1

Current

Electricity

generation

p n

Heater

Heat

sink

ΔV ΔT⇔

Seebeck effect

(ΔT ΔV) : thermogeneratorsPeltier effect

(ΔV ΔT) : cooling

systems

⇒⇒

THot

TCold

S=ΔV/ΔT

c

hm

mCarnot

c

hm

m

h

chmax

TTZT1

1ZT1

TTZT1

1ZT1T

TT

++

−+η=

++

−+−=η

Efficiency

of a thermogenerator

Thermoelectric Generators (TEG)

Module under

test

Te/

TeS/S

S)1()2( μ

→μ+−

=

Limit T →∝ : S ~ entropy / carrier

for T →∝

)x

x1ln(e

kS B −−=

Narrow

band systems

with

strong

interactions : the Hubbard model

+ Spin and/or orbital degeneracy

β )xx-1ln(

ekS B β−=

p typeNax

CoO2

I. Terasaki

Misfit cobaltites

T-independentNot expected

for metal

(Bi0.87 SrO2 )2 (CoO2 )1.82 oxide

Sous réseau 1 [(Bi0.87

SrO2

)2

] : a = 4.90 Å, b1 = 5.11 Å, c = 29.86Å, β

= 93.4°Sous réseau 2 [CoO2

] : a = 4.90 Å, b2 = 2.81 Å, c = 29.86Å, β

= 93.4°b1 /

b2 = 1.82≈

11/6

N = 4

H. Leligny et al,C.R. Acad. Sci. Paris, t.2Série IIc, 409 (1999)

Co network: triangles

Origin

of large S?

Spin and Orbital DegeneracyCo3+

(3d6)/Co4+

(3d5)

LS states due to CdI2 layers

)x1

xggln(

ekS

4

3B

−−=

Localized

picture

: the generalized

Heikes

formula

Maekawa

and cowork. Phys. Rev. B 62, 6869 (2000)

Band structure calculations

:Lifting of the t2g

levels

degeneracy

due to rhombohedral

crystalline

field

of

CdI2

layers

FEE

22

))ln((e3k

TS

==dE

d σπ

D. J. Singh, Phys. Rev. B 61, 13397 (2000)T. Yamamoto et al., Phys. Rev. B 65, 184434 (2002)

Peak

in DOS : large S+ MetallicityAt

high

T

:

Scaling

MR et MTEPLien avec la susceptibilité

MagnetothermopowerMisfit

BiCaCoO

Similar

to Na0.7

CoO2Y. Wang et al., Nature423, 425 (2003)

Scaling

law

for S(H) : paramagnetic

spins S=1/2Brillouin function

P. Limelette et al., PRL97, 046601 (2006)

Decrease

of S in field

at

low

TDue to the alignement of paramagnetic

spins

Peak of susceptibility

NMR

J. Bobroff et al,PRB (LPS Orsay)

0 50 100 150 200 250 3000

20

40

60

80

100

S (μ

V.K-1

)

T (K)

Bi1.95Ba1.95Rh1.9Oα

Bi2Ba2Co2Oα

0 100 200 300 4000

5

10

15

20

MR

(%)

ρ (m

Ω.c

m)

T(K)

0 10 20 30 40 50

-2

0

2

4

6 14T 7T 3.5T

[Bi1.95

Ba1.95

Rh0.1

O4

][RhO2

]1.8

Metallic

down to 50KLarge S

: spin degeneracy

β

= 1/6

Small and positive magneto-resistance

Y. Klein, Phys. Rev. B 73, (2006) 165121

T-independentMetallic

SrRuO3Chemical formula Calculated Ru

oxidation state

SrRuO3 4SrRu0.97

O2.94 4SrRu0.92

O3 4.35SrRu0.975

Cr0.025

O3 4 (for Cr4+)SrRu0.9

Mn0.1

O3 4.11 (for Mn3+)Sr0.8

La0.2

RuO3 3.80

0 50 100 150 2000

10

20

Sr0.8La0.2RuO3

SrRu0.92O3 SrRu0.97O2.94

SrRuO3

SrRu0.975Cr0.025O3

SrRu0.9Mn0.1O3

dc, FC, 1 kOe

M (e

mu/

g)

T (K)

0 50 100 150 200 250 300 350 400

10-3

10-2

SrRuO3

SrRu0.92O3

Sr0.8La0.2RuO3

SrRu0.97O2.94

SrRu0.975Cr0.025O3

SrRu0.9Mn0.1O3

T (K)

ρ (Ω

cm)

0 200 400 600 8000

5

10

15

20

25

30

35

40

Sr2RuO4

CaRu0.8Ga0.2O3

CaRuO3

SrRuO3

S (μ

V.K-1

)

T (K)

Ruthenates: same

behavior

for S(T)

Spin only

contribution, works

in a metallic

compound

Ru3+

/Ru4+

1121)2/1(2

+×+×

=β

Sspin

= 35μV/K

Ru4+

/Ru5+

Sspin

= 25μV/K

0 100 200 300 400 500 600 700 800 900-202468

10121416182022242628303234

La0.5Ca0.5Cu3Ru4O12 LaCu3Ru4O12

S (µ

V.K-1

)

T (K)

0 100 200 300 400 500 600 700 800 9000,0

1,0x10-42,0x10-43,0x10-44,0x10-45,0x10-46,0x10-47,0x10-48,0x10-49,0x10-41,0x10-31,1x10-31,2x10-31,3x10-31,4x10-31,5x10-3

LaCu3Ru4O12

ρ (Ω

.cm

)

T (K)

ACu3

Ru4

O12Large mass enhancement(γ=135mJ/fu.mol.K2 for A=La)ex: RuO2

γ=6mJ/fu.mol.K2S. Tanaka et al, cond-mat 28 june 2009

A. Maignan et al (to be published)

T lineardependence

T lineardependence

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

AMO2

A (dumbell)

MO22H or 3R depending

on

oxygen

packing

PdCoO2

: metal, like

PdDJ Singh

Doped

CuCrO2

: bad

metalwith

large S

Du Pont 1970

Delafossite: layer compound with CdI2 type layer

M network: triangles

0 50 100 150 200 250 300 350 4000,0

1,0x10-5

2,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5

6,0x10-5

7,0x10-5

8,0x10-5

9,0x10-5

TN

CuRh0.9Mg0.1O2

CuCr0.98Mg0.02O2

ZFC, 0.3 T

χ (e

mu.

g-1)

T (K)

CuCr1-x

Mgx

O2 CuRh1-x

Mgx

O2

Triangular

AF S=3/2Pauli paramagnet

S=0

CuRh1-x

Mgx

O2

For large enough

hole

contentmetal-like

behavior

as cobaltites

Experiment

Calculated

SαT

PF is

rather

T independent

CuRh1-x

Mgx

O2

300 400 500 600 700 800 900 1000 1100100120140160180200220240260280300320340

x=0.00

x=0.01 x=0.04

x=0.10

S (µ

V.K-1

)

T (K)

300 400 500 600 700 800 900 1000 11000,0

5,0x10-51,0x10-41,5x10-42,0x10-42,5x10-43,0x10-43,5x10-44,0x10-44,5x10-45,0x10-45,5x10-46,0x10-46,5x10-47,0x10-47,5x10-4

x=0.00

x=0.01

x=0.04

x=0.10

S2 ρ-1 (W

.K-2.m

-1)

T (K)

Large T range for Fermi liquid-like

behavior

Spiral magnets

Spiral magnets breaking inversion symmetry, in an insulator, induces a polarization.

Spin rotation axis

Wave vector of the spiral≠][ QePrrr

×≈

Mostovoy Phys.Rev.Lett.96 067601 (2006)

M. Kenzelmann Phys. Rev. Lett. 95, 087206 (2005)

CFE TT = Ferroelectricity

is induced by magnetic order

Peak in dielectric constant

5 10 15

4.02

4.03

4.04

Ni3V2O8

ε

T(K)

Modulated

antiferromagnetic

structures found

in geometrically frustrated insulating materials

Spin current

model

Antiferromagnetically

stacked

proper

helical

structure (q,q,3/2), q=0.21

][ QePrrr

×≈

BUTe//Q (on average) , P=0

Spin current

model

Crystals

to test for the chirality

Spin current

model

New explanation

is

requiredin doped

CuFeO2

c is

the spin chirality

vector

0 50 100 150 200 250 300 350 40010-1

100

101

102

103

104

105

x = 0.06

x = 0.03

x = 0.01

x = 0.005

x = 0.02

x = 0.00

ρ (Ω

.cm

)

T (K)0 50 100 150 200 250 300

0

200

400

600

800

1000

1200

x = 0.005

x = 0.01x = 0.03

x = 0.04

CuCr1-xMgxO2

x = 0.00

x = 0.06

x = 0.02

S (µ

V.K-1

)

T (K)

Transport properties

of CuCr1-x

Mgx

O2

Large resistivity

drop up tox=0.02

Large S drop up tox=0.02

Holes

: Cr4+

Activated

(x=0.00) to small

polaron

(x>0.01)

Maekawa

TEM/ED/EDX/XRD: xmax

=0.01

Trivalent Cr S=3/2

T (K)0 50 100 150 200 250 300

1/χ

(mol

.em

u-1)

160

180

200

220

240

260

280

μeff = 3.89μΒ

CW = -202K

T (K)5 10 15 20 25 30 35 40

χ (em

u.g-1

)

41x10-6

42x10-6

43x10-6

44x10-6

TN

CuCrO2

SG: R-3m

NTE

No structural transitionKeeps

a centrosymmetric

structure

Undoped: insulator

Trivalent Cr S=3/2

CuCrO2

M. Poienar et al, Phys. Rev. B 79, 014412 (2009)

10-1

100

101

102

103

104

105

0 50 100 150 200 250 300 350

0 25 50 75 1000.000

0.025

0.050

0.075

0.100

0 10 20 30 40 500

5

10

15

20

x = 0 x = 0.02

C (J

.K-1.m

ol-1)

T (K)

CuCr1-xMgxO2

T (K)

ρ (Ω

.cm

)

C/T

(J.K

-2.m

ol-1

)

T2 (K2)

K. Kimura et al, Phys. Rev. B 78, 140401R 2008exp: in-plane polarization

AF, incommensurate propagation vector k = (q, q, 0) with q ≅

0.329(1)

Helicoidal

AF

-10 -5 0 5 10

14

16

18

20

25-25

-20

-15

-10

-5

0

5

10

15

20

25Po

lariz

atio

n(Δ

P(μC

/m2 ))

μ0H(T)

Related

to structural changes

0 5 10 15 20 25T(K)

CuCrO2

TN

Cr [3a (0,0,0)]

Ag [3a (0,0,0.1549(2))]S1

[3a (0,0,0.2691(3))]

S2

[3a (0,0,0.7307(3))]

AgS4

“tetrahedra”

CrS6“octahedra”

a = 3.4961(1)Å

c = 20.5316(5)Å

AgCrS2S O

acentric

R3m rhombohedral

Two sets of three Cr-S interatomic

distances (about 2.386 Å

and 2.447 Å)Different from the 6 equivalent Cr-O distances of delafossites

0

100

200

300

400

0 50 100 150 200 250 300 350 4000,002

0,004

0,006

0,008

0,010

0,012

0,014

0 10 20 30 40 50 60 70 80102

103

TN

CuCrS2

ρ (Ω

.cm

)

T (K)

AgCrS2

CuCrS2

AgCrS2

CuCrS2

χ-1 (m

ol.e

mu-1

)

χ (e

mu.

mol

-1)

T (K)

5,05

5,10

5,15

5,20

40

60

80

100

(a)

ε'

0 5 10 15 20 25 30 35 40 45 50 55 60-25

-20

-15

-10

-5

0

5

10

15

20

0 5 10 1513.0

13.5

14.0

14.5

15.0

P(μ

C/m

2 )

B(T)

(b)

ΔP (μ

C/m

2 )

T(K)

χ (μ

emu.

g-1)

K. Singh et al, Chem. Mater. 2009, 21 (21), pp 5007–5009

AgCrS2

AF insulator

JT-cation: CuMnO2

JT distortion

lifts the eg

orbital degeneracyOrbital ordering

crednerite

C2/m

NaMnO2M. Jansen and R. Hoppe, Zeitschrift Fur Anorganische Und Allgemeine Chemie 399, 163 (1973)S=2

a = 5.5945(2)Å, b = 2.8847(1)Å, c = 5.8935(2)Å

and b = 103.97(2)°

propagation vector k1 = (-½

½

½)

F. Damay et al , Phys. Rev. B 80, 094410 (2009)

TN

=65K

monoclinic (C2/m) to strained triclinic C 1

Anisotropic

magnetic

in-plane

interactions

No magnetoelectric

properties

Plan:

3D magnetic

networks:CMR in perovskite

manganites

MIT in cobaltitesFrustrated

lattices

of the «

114

»

type

1D and 2D TM-O-TM

networks: hexagonal perovskitesand CdI2

type structures

n-type vs p-type

conductivity

in oxides

T)(

STSZTle

22

κ+κρ=

ρκ=

Degenerate

semiconductors

, best TE

n type

TCO physics:

Zn1-x

Alx

O (x = 0 –

0.1)ZT = 0.6

M. Ohtaki et al

0 200 400 600 800 1000

1,0x10-2

2,0x10-2

3,0x10-2

4,0x10-2

5,0x10-2

6,0x10-2

7,0x10-2

0.0075 0.005

0.0025

0.03

0.01

ρ (Ω

.cm

)T (K)

ρ

minimum for x=0.01

Zn1-x

Alx

O

Proceedings

ICT 2008

Zn1-x

Alx

O

300 400 500 600 700 800 900 1000 1100-230-220-210-200-190-180-170-160-150-140-130-120-110

0.0075

0.005

0.0025

0.03

0.02

0.01

S (µ

V.K-1

)

T (K)|S|

minimum for x=0.01

FEE

2B

2

)E

)E(ln(T3ek

S =∂∂

=σπ

Not able to reproduce

Pb1.6

V8

O16 1D structure

I12/m1 space group with a=10.125Å, b=2.902Å

and c=9.880Å

1.4e-

in the V empty t2g

orbitalsn type?

Hollandite

300 400 500 600 700 800 9002,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5

6,0x10-5

7,0x10-5

8,0x10-5

9,0x10-5

S2 ρ-1 (V

2 .K-2.Ω

-1.m

-1)

T (K)

1,0x104

2,0x104

3,0x104

4,0x104

5,0x104

6,0x104

7,0x104

8,0x104

9,0x104

1,0x105

1,1x105

1,2x105

1,3x105

0 50 100 150 200 250 300 350 4000,0

1,0x10-5

2,0x10-5

3,0x10-5

4,0x10-5

5,0x10-5

6,0x10-5

7,0x10-5

8,0x10-5

100 110 120 130 140 150 160 170 180 190 2009,00x10-6

9,20x10-6

9,40x10-6

9,60x10-6

9,80x10-6

1,00x10-5

1,02x10-5

1,04x10-5

fcc fcw

χ (e

mu.

g-1)

T (K)

fccfcw

fcw

χ (e

mu.

g-1)

T (K)

χ -1 (g

.em

u-1)

10-3

10-2

10-1

100

101

102

103

104

105

106

0 100 200 300 400 500 600 700 800 900-45

-40

-35

-30

-25

-20

-15

-10

-5

ρ (Ω

.cm

)

S (µ

V.K-1

)

T (K)

TN

TN

Pb1.6

V8

O16

1.7 mΩ.cm to 2.2 mΩ.cm

300K 100K

From

ED:no struct.transition

n type!

a1a2

c

V2

O9

dimmers

Pb

V in VO5trigonal bipyramid

a

c

a b

VO6

octahedra

layer

PbV6

O11

5/3 e-

in the V empty t2g

orbitals

kagome

RT : 5.7567(1) Å

and 13.2662(2) ÅP63

mc

-8 -6 -4 -2 0 2 4 6 80,70

0,75

0,80

0,85

0,90

0,95

1,00

-4 -3 -2 -1 0 1 2 3 40.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

1.02 20 K

ρ(H

) / ρ

(H =

0)

µ0H (T)

200 K150 K

120 K

100 K

90K40K60K

20K

PbV6O11

ρ(H

) / ρ

(H =

0)

µ0H (T)

-8 -6 -4 -2 0 2 4 6 8-18-15-12-9-6-30369

121518

120K 90K 60K 20K

PbV6O11

M (e

mu.

g-1)

µ0H (T)

PbV6

O11

SPINTRONIC

A.Maignan et al, APL (in press)

Ferro. Like

component

0,0010 0,0015 0,0020 0,0025 0,0030

-20-18-16-14-12-10-8-6-4-202468101214

300 400 500 600 700 800 900-20-18-16-14-12-10-8-6-4-202468

101214

S (µ

V.K-1

)

T -1 (K-1)

S (µ

V.K-1

)

T (K)

0 100 200 300 400 500 600 700 800 90010-2

10-1

100

101

102

103

104

105

106

0,000 0,005 0,010 0,015 0,02010-2

10-1

100

101

102

103

ρ (Ω

.cm

)

T -1 (K)

ρ (Ω

.cm

)

T (K)

0 50 100 150 200 250 300 350 4000,0

5,0x10-31,0x10-21,5x10-22,0x10-22,5x10-23,0x10-23,5x10-24,0x10-24,5x10-25,0x10-25,5x10-26,0x10-26,5x10-2

fc

zfc

χ (e

mu.

g-1)

T (K)

TC

TC P63/mmcP63mc

PbV6

O11

Structural transitionFrustration is

lifted

n type

Conclusions :

Many

things

still

to be

discovered

in oxides

!!!!!!!!!!!

Decreasing

the thermal conductivity

: polyanions

?

Electronic

correlations, spin/charge/orbital coupling

Thanks

to my

Colleagues

Christine Martin, Denis Pelloquin, Sylvie HébertRaymond Frésard, Oleg Lebedev, Charles Simon,Vincent Caignaert, Valérie Pralong, Bernard Raveau

andLPS, UJF, IPCMS, ICMCBLLB, ILL, ISIS, MPI Dresden, Koeln

and Augsburg

Univ. ,

NIU

and

Post-docs, PhDs