title: One-dimensional instability in BaVS3.
abstract: The 3d(1) system BaVS3 undergoes a series of remarkable electronic phase transitions. We show that the metal-insulator transition at T(MI)=70 K is associated with a structural transition announced by a huge regime of one-dimensional (1D) lattice fluctuations, detected up to 170 K. These 1D fluctuations correspond to a 2k(F)=c(*)/2 charge-density wave (CDW) instability of the d(z(2)) electron gas. We discuss the formation below T(MI) of an unconventional CDW state involving the condensation of the other V4+ 3d(1) electrons of the quasidegenerate e(t(2g)) orbitals. This study stresses the role of the orbital degrees of freedom in the physics of BaVS3 and reveals the inadequacy of current first principle band calculations to describe its electronic ground state.
authors.affiliation: Laboratoire de Physique des Solides (CNRS-UMR 8502), Université Paris-Sud, Orsay, France.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Fagot
authors.forename: Pascale
authors.initials: P
authors.lastname: Foury-Leylekian
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ravy
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Pouget
authors.forename: Helmuth
authors.initials: H
authors.lastname: Berger