Charge ordering in substituted and non-stoichiometric BaVS3

International audienceAmong the correlated electronic systems, BaVS3 which exhibits both itinerant and localized states as well as a subtle interplay betwen charge, orbital, spin and lattice degrees of freedom, is a model system. Its electronic structure consists in a broad quasi–one-dimensional (1D) dz2 band and two quasi-degenerate narrow e(t2g) bands. Pure BaVS3 exhibits a metalinsulator transition (MIT) driven by a Peierls instability in the dz2 band. We present a structural investigation showing that in chemically substituted Ba1−xSrxVS3 and in non-stoichiometric BaVS3−, the commensurate Peierls distortion of BaVS3 is replaced by an incommensurate modulation that we attribute to a charge ordering (CO) of the localized e(t2g) electrons. This unexpected structural feature is discussed in relationship with the concomitant drastic change of magnetic properties of the system