p. foury-leylekian 1, ph. leininger 2, v. ilakovac 3 y. joly 4, j.-p. pouget 1 ground state of the...

P. Foury-Leylekian1, Ph. Leininger2, V. Ilakovac3 Y. Joly4, J.-P. Pouget1

GROUND STATE OF THE QUASI-1D CORRELATED ELECTRONIC SYSTEM BaVS3

1 Laboratoire de Physique des Solides, Univ. Paris 11, Orsay , France2 Max-Planck-Institut Stuttgart, Germany

3 LCP-MR, Université Pierre et Marie Curie, Paris, France4 Institut Néel, CNRS-UJF, Grenoble, France

ECRYS 2011, Cargèse

INTRODUCTION

LOW DIM. NON INTERACTING ELECTRON GAS + LATTICE COUPLING = 2kF CDW+ PEIERLS TRANSITION

PLD

(x)

CDW

(x) = - u(x)/x

uq

u(x)

2kF

gap 2(spin and charge sector) insulating ground state ECRYS 2011, Cargèse

Fermi surface nesting

(q)(q)

q=(2kF,…)

INFLUENCE OF THE ELECTRONIC CORRELATION ON THE LOW DIMENSIONAL ELECTRON GAS

V

4KF

SDW

2KF(q)

CDWs

t

U>0ST (SS)

ECRYS 2011, Cargèse

g1 (= U+2V1cos)

superconductivityDW

(H. Schultz)

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STRONG CORRELATIONS + LATTICE COUPLING

S. Mazumdar et al 2000D. Poilblanc et al 2000

BOW

site CDW

δ-(EDT-TTF-CONMe2)2Br

2a*-c*

b*

qc

Blue bronzea*

MULTIBAND EFFECTS … ORBITAL DEGREES OF FREEDOM ?

ECRYS 2011, Cargèse

P4W8O32 Blue bronze

E. Sandre, P. Foury et al PRL 01

BaVS3

F. Lechermann et al 2007J.P. Pouget et al 1983

Hidden nesting of 2 bands simultaneously

Interband nesting ? ?

PURE BaVS3

ECRYS 2011, Cargèse

V

B

anisotropy structural 1D Å 6.75c VV

Å 2.8c // VV

S

STRUCTURE OF THE QUASI-1D CORRELATED ELECTRONIC SYSTEM BaVS3

ELECTRONIC STRUCTURE

Spliting of the dz2 and et2g levels

LDA : 2 types of non degenerated bands

Ba2+ V4+ S2-3

V : 3d1

dz2 : quasi-1D wide band

(conduction) 94% filled

e(t2g) : 3D narrow band (magnetism)

2 V per unit cell n(dz2)+n(e(t2g))=2

F. Lechermann et al 2007

ECRYS 2011, Cargèse

Structural transition at Ts=240K

Hexagonal Orthorhombic (Cmc21)

S. Fagot et al SSS 05

c

T > TS T < TS

Cmc21

SUCCESSION OF PHASE TRANSITIONS

Metal-Isulator Transition(MIT) at TMI=70K

Unusual features

G. Mihaly et al, PRB 00

Mihaly et al, Phys. Rev. B 61, R7831 (2000)

Magnetic susceptibility

Resistivity

TMI

TMI

Transition at Tx=30K

Magnetic origin????

Tx

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MIT TRANSITION

PEIERLS-LIKE TRANSITION

T. Inami et al, PRB 02

PLD at q=(1,0,1/2)+2q

1D regim of fluctuations

20 40 60 80 100 120 140

130

135

140

145

150

155

160

165

170

(1 5 0)

inte

nsity

(arb

itrar

y uni

t)

T (K)

10 20 30 40 50 60 70 800123456789

(-1 4 -2.5)

inte

nsity

(arb

itrar

y un

it)

T (K)

S. Fagot et al, PRL 04

Peirls-like transition with a 2kF CDW of dZ2 e-

2kF=1/2c* (1/4 filling) for dZ2 band?

Powder structural refinement

S. Fagot et al, SSS 05

+ -0 0 + -0

S. Fagot et al PRB 06

Resonant X-ray scattering

ECRYS 2011, Cargèse

2kF(dz2)=1/2c* determined by X-ray :- Not agree with LDA calculation but with DMFT

- Agree with Magnetic susceptibility (Curie const. n(et2g)=2-n(dz2)=12kF(dz2)=1/2c*)

includes U = intrasite Coulomb repulsion J = Hund coupling

Lechermann et al, PRL 94, 166402 (2005)

dz2

e(t2g)

1/2

DMFT CALCULATIONS

ECRYS 2011, Cargèse

MIT TRANSITION

PEIERLS-LIKE TRANSITION

T. Inami et al, PRB 02

PLD at q=(1,0,1/2)+2q

1D regim of fluctuations

20 40 60 80 100 120 140

130

135

140

145

150

155

160

165

170

(1 5 0)

inte

nsity

(arb

itrar

y uni

t)

T (K)

10 20 30 40 50 60 70 800123456789

(-1 4 -2.5)

inte

nsity

(arb

itrar

y un

it)

T (K)

S. Fagot et al, PRL 04

Peirls-like transition with a 2kF CDW of dZ2 e-

2kF=1/2c* (1/4 filling) for dZ2 band?

Tetramerisation of the V4+ chain

Absence of CO of V4+

Powder structural refinement

S. Fagot et al, SSS 05

+ -0 0 + -0

S. Fagot et al PRB 06

Resonant X-ray scattering

ECRYS 2011, Cargèse

cdz²

e(t2g)

2kF CDW

dz²

4kF CDW

e(t2g)

V1

V2

V4

V3

V1

INTERPRETATION : ORBITAL ORDER

S1

S1

S2S2

S2S2

ΔV-SG

ΔV-S2

ΔV-S1

0.100.040.120.14

0.080.130.080.02

0.500.370.530.47

V4V2 V3V1

V-S distances

ECRYS 2011, Cargèse

INFLUENCE OF DOPING

S DEFICIENT COMPOUNDS (5-10%)

A new instability at q’

- n(dz2)+n(e(t2g))>2 - HO transition shifted at low temperature

- Semiconducting behaviour

- SRO q’=(2/3,0,0.21±0.01) at Tc~140K

- 3D regim of fluctuations

CDW=2/34/3

0

ECRYS 2011, Cargèse

c*

• MIT persists : Tc=70K ~40K• Modulation q=(1,0,1/2±0.01) at TMI

• 1D fluctuation regime?

• Semiconducting state

• SRO q’=(2/3,0,.165±.01)

• Tc>200K • 3D fluctuation regime

c*

BaSr0.15VS3BaSr0.10VS3 S. (Bernu et al, EPL 2010)

Sr SUBSTITUTED COMPOUNDS

STRUCTURAL FEATURES

Sr>12% Sr>12% same q’ instability as in S deficient compounds

Strong sensibility of q(MIT) to any kind of perturbation

Sr<12%

ECRYS 2011, Cargèse

INFLUENCE OF DOPING : CONCLUDING REMARKS

• Commensurate PLD persits

• lock-in lattice effects ?

• 1/2 filling of dz2: not strickly ?

F. Lechermann et al, PRL 05

New q’ instability : CO of all e(t2g) e-

q’//c*(=0.165 or 0.83 for Sr15%) gives n(e(t2g)) : (n(e(t2g))=0.835 n(dz2)=1.165 : agrees with critical value)

3D regim of fluctuation (q’) because of 3D character of et2g orbitales

Strong doping

ECRYS 2011, Cargèse

Weak doping

GROUND STATE

W. Higemoto 02 H. Nakamura 00

GROUND STATE BELOW Tx ?

MuSR PND

- Magnetic origin

- qHex=(0.226, 0.226, 0) Validation on single crystal?

- Easy plane (a,b)

Mihaly 00

Susceptibility

Tx

ECRYS 2011, Cargèse

RESONANT MAGNETIC X-RAY SCATTERING RMXS OF BAVS3 AT THE V- L3 EDGE

Polarisation analysis and azymuthal angle dependence Orientation of Magnetic Moment

I~

Initial state

Final sate

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MAGNETIC REFLECTION DETECTED ON SINGLE CRYSTAL

- qHex magnetic reflex detected for the first time on single crystal

- qHex=(0.226, 0.226, ) with =0.033

Resonance of the reflection at qHex Magnetic character Presence of 2 reflections along

c*qHex is triply commensurate

2

~ l scan

~ h scan

0

P. Leininger et al, PRL 2011

ECRYS 2011, Cargèse

AZIMUT DEPENDENCE MOMENT ORIENTATION

- I/I max at =0 M is in the (a,b) plane

- Complexe magnetic structure requires modelization

I~

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MODELISATION USING FDMNES : DIFFICULTIES

6 twin domains due to HO transition

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8 V/unit cell - more in the magnetic cell

Only one reflection detected at this energy

commensurate approx. qhex=(0.25 0.25 0)H

FDMNES MODELISATION : APPROXIMATIONS

ECRYS 2011, Cargèse

aM

bM

Model 1 :supercell (1x2x1)

qMon=(0 -1/2 0)M supercell (1x2x1)

Less reliable because AF along the long V-V distance

qMon=(1/4 1/4 0)M supercell (4x4x1)

Model 2 :supercell (4x4x1)

RESULT OF THE FIT

ECRYS 2011, Cargèse

Good agreement fit/result I(E) and I() Model 1 is reliable

P. Leininger at al, PRL 11

Origin of the c* component of qhex? Conical magnetic structure ?

Origin of the magnetic ground state? A 4kF CDW of et2g ?

GROUND STATE

bM

aM

- L. Forro, N. Barisic, A. Akrap (EPFL, Suisse)

- H. Berger (ICM, Suisse), A. Gauzzi (IMPMC, Paris)

- M. Greenblatt, M. Lobanov, G. Popov (Rutgers, USA)

- A. Georges, S. Biermann, F. Lechermann (CPHT, X)

- M. Anne, E. Lorenzo, Y. Joly (Labo de cristallo, Grenoble)

- S. Ravy, P. Fertey (SOLEIL), V. Ilakovac (CCR, Paris)

- M.H. Lemée-Caillot (ILL, Grenoble)

- P. Cenzier, C. Pasquier (LPS, Orsay)

Theses :

-S. Fagot (05)

-S. Bernu

ECRYS 2011, Cargèse

Collaborations :

Ph. Leininger, V. Ilakovac Y. Joly, J.-P. Pouget

DIFFUSION : A POWERFULL TOOL

BaVS3 S. Fagot, P. Foury et al PRL 03

ξ//-1

ξ//

(2kF)-1

1D

ξ//

(2kF)-1

ξ┴

(2kF)

3D

(I~2 )

Diffuse scattering

Reciprocal Direct

CO

Resonant diffraction

Initial state

Final sate

Eedge

f’

f’’

ISat

-

+

-

+

-

+

I

E(eV)

NaV2O5, S. Grenier et al PRB 02

Sensible to CO… Sensible to SR and LRO magnetism…

L-edgeK-edge

DyMn2O5, Ewing et al 08

U<0: Luther Emery liquid

U>0: Luttinger liquid

2kF « site » CDW - no magnetism

AF

SP

2kF SDW

2kF « bond » CDW  (BOW)

ECRYS 2011, Cargèse

GROUND STATES

I) Introduction

II) Metal-Insulator transition of pure BaVS3

III) Influence of external fields : doping, pressure

IV) Magnetic ground state

V) Perspectives

OUTLOOK

ECRYS 2011, Cargèse

*4kF CDW could result from a RKKY indirect Coulomb coupling between the localized e(t2g) charges via the 2kF CDW fluctuations

(2kF)-1 =2c

If so: the 4kF CDW and 2kF CDW are out of phase

at TMI = 70 K: 2kF CDW in the dz² quasi-1D band

Gap opens in the charge and spin sectors

4kF CDW induced* within the quasi-degenerated e(t2g) electrons

Gap opens only in the charge sectore(t2g) spin degrees of freedom remain available for the 30K magnetic transition

S DEFICIENT COMPOUNDS (5-10%)

A new instability at q’

- n(dz2)+n(e(t2g))>2 - HO transition shifted at low temperature

- Semiconducting behaviour

- SRO q’=(2/3,0,0.21±0.01) at Tc~140K

- 3D regim of fluctuations

CDW=2/34/3

0

ECRYS 2011, Cargèse

(A. Gauzi et al Eur. Lett. 06))

INFLUENCE OF DOPING : CONCLUDING REMARKS

• 1/2 filling of dz2: not strickly 2kF=1/2+q ?

• lock-in lattice effects q=(1,0,1/2) CDW

F. Lechermann et al, PRL 05

• q’ instability, a CO of all e(t2g) e- q’//c*(=0.165 or 0.835 for Sr15%) gives n(e(t2g))

n(e(t2g))=0.835 n(dz2)=1.165 :agrees with critical value

3D regim of fluctuation (q’) because of 3D character of et2g orbitales

• Commensurate q CDW of the dz2 e- distroyed :

if δqc*ξth(TMI)>1 δqc>0.07c* nc(dz2)=1+2qc=1.14

For Tc : Ln[Tc(x)/TMI] [δqcξth(TMI)]2 Tc~30K

(A. Gauzi et al Eur. Lett. 06))

ECRYS 2011, Cargèse

COMMENSURABILITY EFFECTS

Incomm.

2kF=1/2a*

Soliton lattice

Sr SUBSTITUTED COMPOUNDS

•Tx persists

• Semiconducting state• FM behaviour

Sr<~12% Sr>~12%

(A. Gauzi et al Eur. Lett. 06))

ECRYS 2011, Cargèse