First-principles study of charge-ordered insulating phases in Ruddlesden-Popper LaSr2V2O7

초록

We investigate the electronic properties of Ruddlesden-Popper LaSr2V2O7 using first-principles density functional theory. By substituting La to Sr in the experimentally reported Ruddlesden-Popper Sr3V2O7 we find the charge -ordered insulating phases. The charge ordering is induced from the average nominal valence of V3.5+ by La -substitution, which in turn disproportionates to a 1:1 ratio of V4+ and V3+ sites. The charge ordering is accompanied by the uniaxial Jahn-Teller distortion compatible with the charge ordering pattern where compression (elongation) along the [110]-direction lowers dxz (dxy/dyz) orbitals with respect to the other t2g orbitals. The comparison of total energies with different charge and magnetic ordering patterns shows that the ground state is insulating with a checkerboard-type of charge ordering and an A-type (layered) antiferromagnetic ordering. Our work, proposing a new charge-ordered insulating phase by A-site substitution, provides an effective way to design insulating oxides with charge ordering.

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