Electronic structure and magnetic interactions in LiV ₂ O ₄

Abstract

We present results of all-electron electronic structure calculations for the\nrecently discovered d electron heavy fermion compound LiV_2O_4. The augmented\nspherical wave calculations are based on density functional theory within the\nlocal density approximation. The electronic properties near the Fermi energy\noriginate almost exclusively from V 3d t_{2g} states, which fall into two\nequally occupied subbands: While sigma-type metal-metal bonding leads to rather\nbroad bands, small pi-type p-d overlap causes a narrow peak at E_F. Without the\ngeometric frustration inherent in the crystal structure, spin-polarized\ncalculations reveal an antiferromagnetic ground state and ferromagnetic order\nat slightly higher energy. Since direct d-d exchange interaction plays only a\nminor role, ordering of the localized vanadium moments can be attributed\nexclusively to a rather weak superexchange interaction. With the magnetic order\nsuppressed by the geometric frustration, the remaining spin fluctuations\nsuggest an explanation of the low temperature behaviour of the specific heat.\n