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P. Foury-Leylekian 1 , Ph. Leininger 2 , V. Ilakovac 3 Y. Joly 4 , J.-P. Pouget 1

GROUND STATE OF THE QUASI-1D CORRELATED ELECTRONIC SYSTEM BaVS 3. P. Foury-Leylekian 1 , Ph. Leininger 2 , V. Ilakovac 3 Y. Joly 4 , J.-P. Pouget 1. 1 Laboratoire de Physique des Solides, Univ. Paris 11, Orsay , France 2 Max-Planck-Institut Stuttgart, Germany

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P. Foury-Leylekian 1 , Ph. Leininger 2 , V. Ilakovac 3 Y. Joly 4 , J.-P. Pouget 1

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  1. GROUND STATE OF THE QUASI-1D CORRELATED ELECTRONIC SYSTEM BaVS3 P. Foury-Leylekian1, Ph. Leininger2, V. Ilakovac3 Y. Joly4, J.-P. Pouget1 1 Laboratoire de Physique des Solides, Univ. Paris 11, Orsay , France 2 Max-Planck-Institut Stuttgart, Germany 3 LCP-MR, Université Pierre et Marie Curie, Paris, France 4 Institut Néel, CNRS-UJF, Grenoble, France ECRYS 2011, Cargèse

  2. INTRODUCTION

  3. CDW Fermi surface nesting PLD uq u(x) r(x) r(x) = - du(x)/dx c(q) c(q) q=(2kF,…) 2kF gap 2D (spin and charge sector)insulating ground state LOW DIM. NON INTERACTING ELECTRON GAS + LATTICE COUPLING = 2kFCDW+ PEIERLS TRANSITION ECRYS 2011, Cargèse

  4. t INFLUENCE OF THE ELECTRONIC CORRELATION ON THE LOW DIMENSIONAL ELECTRON GAS CDWs g1 (= U+2V1cosrp ) 2KF c(q) U>0 ST (SS) 4KF Kr V superconductivity DW SDW (H. Schultz) ECRYS 2011, Cargèse

  5. STRONG CORRELATIONS + LATTICE COUPLING b* a* Blue bronze 2a*-c* qc BOW site CDW D. Poilblanc et al 2000 S. Mazumdar et al 2000 δ-(EDT-TTF-CONMe2)2Br ECRYS 2011, Cargèse

  6. MULTIBAND EFFECTS … ORBITAL DEGREES OF FREEDOM ? Blue bronze BaVS3 P4W8O32 F. Lechermann et al 2007 J.P. Pouget et al 1983 E. Sandre, P. Foury et al PRL 01 Hidden nesting of 2 bands simultaneously Interband nesting ?? ECRYS 2011, Cargèse

  7. PURE BaVS3

  8. STRUCTURE OF THE QUASI-1D CORRELATED ELECTRONIC SYSTEM BaVS3 S V B ECRYS 2011, Cargèse

  9. ELECTRONIC STRUCTURE Ba2+V4+S2-3  V : 3d1 dz2 : quasi-1D wide band (conduction) 94% filled O 2 V per unit cell n(dz2)+n(e(t2g))=2 e(t2g) : 3D narrow band (magnetism) F. Lechermann et al 2007 LDA : 2 types of non degenerated bands Spliting of thedz2and et2g levels ECRYS 2011, Cargèse

  10. Structural transition at Ts=240K Hexagonal  Orthorhombic (Cmc21) S. Fagot et al SSS 05 T > TS T < TS Resistivity c TMI G. Mihaly et al, PRB 00 Cmc21 Metal-Isulator Transition(MIT) at TMI=70K Unusual features Tx Magnetic susceptibility TMI Transition at Tx=30K Magnetic origin???? Mihaly et al, Phys. Rev. B 61, R7831 (2000) SUCCESSION OF PHASE TRANSITIONS ECRYS 2011, Cargèse

  11. + + + 0 0 0 0 0 0 - - - MIT TRANSITION  PEIERLS-LIKE TRANSITION Powder structural refinement PLD at q=(1,0,1/2)+2q 1D regim of fluctuations Resonant X-ray scattering T. Inami et al, PRB 02 S. Fagot et al, SSS 05 S. Fagot et al PRB 06 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? ECRYS 2011, Cargèse

  12. DMFT CALCULATIONS 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)=12kF(dz2)=1/2c*) dz2 1/2 e(t2g) Lechermann et al, PRL 94, 166402 (2005) includes U = intrasite Coulomb repulsion J = Hund coupling ECRYS 2011, Cargèse

  13. + + + 0 0 0 0 0 0 - - - MIT TRANSITION  PEIERLS-LIKE TRANSITION Powder structural refinement PLD at q=(1,0,1/2)+2q 1D regim of fluctuations Resonant X-ray scattering T. Inami et al, PRB 02 S. Fagot et al, SSS 05 S. Fagot et al PRB 06 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+ ECRYS 2011, Cargèse

  14. INTERPRETATION: ORBITAL ORDER 2kF CDW dz² 4kF CDW e(t2g) S2 S1 S2 e(t2g) V1 S1 S2 S2 V2 c dz² V3 V-S distances V1 V2 V3 V4 V4 ΔV-S1 0.47 0.53 0.37 0.50 ΔV-S2 0.02 0.08 0.13 0.08 ΔV-SG 0.14 0.12 0.04 0.10 V1 ECRYS 2011, Cargèse

  15. INFLUENCE OF DOPING

  16. fCDW=2p/3 4p/3 0 S DEFICIENT COMPOUNDS (5-10%) • 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 • A new instability at q’ ECRYS 2011, Cargèse

  17. Sr SUBSTITUTED COMPOUNDS STRUCTURAL FEATURES • Semiconducting state • SRO q’=(2/3,0,.165±.01) • Tc>200K • 3D fluctuation regime • MIT persists : Tc=70K ~40K • Modulation q=(1,0,1/2±0.01) at TMI • 1D fluctuation regime? c* c* BaSr0.10VS3 S. (Bernu et al, EPL 2010) BaSr0.15VS3 Sr<12% Sr>12% • Sr>12% same q’ instability as in S deficient compounds • Strong sensibility of q(MIT) to any kind of perturbation ECRYS 2011, Cargèse

  18. INFLUENCE OF DOPING : CONCLUDING REMARKS Weak doping • Commensurate PLD persits • lock-in lattice effects ? • 1/2 filling of dz2: not strickly ? F. Lechermann et al, PRL 05 Strong doping • 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 ECRYS 2011, Cargèse

  19. GROUND STATE

  20. GROUND STATE BELOW Tx ? Susceptibility MuSR PND Tx Mihaly 00 W. Higemoto 02 H. Nakamura 00 • Magnetic origin • qHex=(0.226, 0.226, 0)  Validation on single crystal? • Easy plane (a,b) ECRYS 2011, Cargèse

  21. Final sate Initial state RESONANT MAGNETIC X-RAY SCATTERING RMXS OF BAVS3 AT THE V- L3 EDGE Y I~ Polarisation analysis and azymuthal angle dependence  Orientation of Magnetic Moment ECRYS 2011, Cargèse

  22. MAGNETIC REFLECTION DETECTED ON SINGLE CRYSTAL 2x 0 ~ l scan P. Leininger et al, PRL 2011 ~ h scan Resonance of the reflection at qHex Magnetic character Presence of 2 reflections along c*qHex is triply commensurate • qHex magnetic reflex detected for the first time on single crystal • qHex=(0.226, 0.226, x) with x=0.033 ECRYS 2011, Cargèse

  23. AZIMUT DEPENDENCE MOMENT ORIENTATION I~ • Is/Ip max at Y=0 M is in the (a,b) plane • Complexe magnetic structure requires modelization ECRYS 2011, Cargèse

  24. 8 V/unit cell - more in the magnetic cell 6 twin domains due to HO transition Only one reflection detected at this energy MODELISATION USING FDMNES : DIFFICULTIES ECRYS 2011, Cargèse

  25. qMon=(0 -1/2 0)M supercell (1x2x1) qMon=(1/4 1/4 0)M supercell (4x4x1) bM Model 2 :supercell (4x4x1) aM Model 1 :supercell (1x2x1) FDMNES MODELISATION : APPROXIMATIONS commensurate approx. qhex=(0.25 0.25 0)H Less reliable because AF along the long V-V distance ECRYS 2011, Cargèse

  26. RESULT OF THE FIT P. Leininger at al, PRL 11 Good agreement fit/result I(E) and I(Y)  Model 1 is reliable ECRYS 2011, Cargèse

  27. GROUND STATE bM aM  Origin of the c* component of qhex?  Conical magnetic structure ?  Origin of the magnetic ground state? A 4kF CDW of et2g ?

  28. Collaborations : Ph. Leininger, V. Ilakovac Y. Joly, J.-P. Pouget • 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

  29. DIFFUSION : A POWERFULL TOOL ξ// 3D ξ┴ (2kF) (2kF)-1 (I~h2 ) Diffuse scattering Resonant diffraction Final sate Direct Reciprocal K-edge L-edge Initial state CO I f’ - + - + - + f’’ ISat E edge ξ//-1 ξ// 1D (2kF)-1 BaVS3 S. Fagot, P. Foury et al PRL 03 DyMn2O5, Ewing et al 08 E(eV) NaV2O5, S. Grenier et al PRB 02 Sensible to SR and LRO Sensible to CO… magnetism…

  30. GROUND STATES U<0: Luther Emery liquid 2kF « site » CDW - no magnetism U>0: Luttinger liquid 2kF SDW AF 2kF « bond » CDW  (BOW) SP ECRYS 2011, Cargèse

  31. OUTLOOK • Introduction • Metal-Insulator transition of pure BaVS3 • Influence of external fields : doping, pressure • Magnetic ground state • Perspectives ECRYS 2011, Cargèse

  32. 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 sector e(t2g) spin degrees of freedom remain available for the 30K magnetic transition *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

  33. fCDW=2p/3 4p/3 0 S DEFICIENT COMPOUNDS (5-10%) • 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 • A new instability at q’ ECRYS 2011, Cargèse

  34. (A. Gauzi et al Eur. Lett. 06)) (A. Gauzi et al Eur. Lett. 06)) INFLUENCE OF DOPING : CONCLUDING REMARKS • 1/2 filling of dz2: not strickly  2kF=1/2+dq ? • lock-in lattice effects  q=(1,0,1/2) CDW F. Lechermann et al, PRL 05 • Commensurate q CDW of the dz2 e- distroyed : • if δqc*ξth(TMI)>1 δqc>0.07c*  nc(dz2)=1+2dqc=1.14 • For Tc : Ln[Tc(x)/TMI]  [δqcξth(TMI)]2 Tc~30K • 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

  35. COMMENSURABILITY EFFECTS Incomm. 2kF=1/2a* Soliton lattice ECRYS 2011, Cargèse

  36. (A. Gauzi et al Eur. Lett. 06)) Sr SUBSTITUTED COMPOUNDS • Tx persists • Semiconducting state • FM behaviour Sr<~12% Sr>~12% ECRYS 2011, Cargèse

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