Structural instabilities in Nb, Ti and K substituted BaVS3
Résumé
The one-dimensional (1D) strongly correlated BaVS3 undergoes a series of unexplained phase transitions. Among them it undergoes a metal-insulator (MI) transition associated with a 2 kF = c* / 2 charge density wave (CDW) instability. We show that this CDW ground state is very sensitive to chemical substitutions and/or sulfur deficiency. Substitutions of V with ≈ 2 % of Nb, Ti or Ba with ≈ 2 % K in probably sulfur deficient samples leads to a completely different ground state. This ground state is characterized by a short range structural modulation with the incommensurate wave vector qS = ( frac(1, 3) frac(1, 3) 0.21 )H, which could be due to a CDW taking place in a differently filled dz2 band.