p. foury-leylekian 1, ph. leininger 2, v. ilakovac 3 y. joly 4, j.-p. pouget 1 ground state of the...
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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)
ECRYS 2011, Cargèse
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
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?
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
ECRYS 2011, Cargèse
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