Charge ordering in substituted and non-stoichiometric BaVS3

Among 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) d(z2) band and two quasi-degenerate narrow e(t(2g)) bands. Pure BaVS3 exhibits a metal-insulator transition (MIT) driven by a Peierls instability in the d(z2) band. We present a structural investigation showing that in chemically substituted Ba1-xSrxVS3 and in non-stoichiometric BaVS3-delta, the commensurate Peierls distortion of BaVS3 is replaced by an incommensurate modulation that we attribute to a charge ordering (CO) of the localized e(t(2g)) electrons. This unexpected structural feature is discussed in relationship with the concomitant drastic change of magnetic properties of the system. Copyright (C) EPLA, 2010