Analysis of the Electron Localization, the Anisotropy of Electrical Conductivity, the Orbital Ordering, and SpinExchange Interactions in BaVS3 on the Basis of First Principles and Semi-empirical Electronic Structure Calculations

The electrical transport and magnetic properties of BaVS3, made up of individual VS3 octahedral chains, were examined on the basis of first principles and tight-binding electronic structure calculations. The electrical conductivity of BaVS3 is nearly isotropic despite its one-dimensional structural feature, because of the orbital interactions associated with the short S···S contacts within each VS3 chain and between adjacent VS3 chains. The probable cause for the metal–insulator transition at ~70 K was examined in terms of first principles electronic structure calculations, which indicate that the metallic and magnetic insulating states of BaVS3 are nearly the same in energy. This is consistent with the observation that the metal–insulator transition at ~70 K is caused by electron localization. The observed magnetic properties of BaVS3 below ~70 K are readily explained under the assumption that the symmetry-broken t2g-orbitals act as the magnetic orbitals in the magnetic insulating state of BaVS3. The probable cause for the latter was discussed.