Electronic structure and magnetic interactions in LiV2O4

TL;DR

This study uses all-electron calculations to explore the electronic structure and magnetic interactions in LiV2O4, revealing the origin of its heavy fermion behavior and the role of geometric frustration in magnetic ordering.

Contribution

It provides a detailed electronic and magnetic analysis of LiV2O4 using density functional theory, highlighting the effects of geometric frustration and superexchange interactions.

Findings

V 3d t2g states dominate near the Fermi level

Geometric frustration suppresses magnetic order

Weak superexchange explains magnetic interactions

Abstract

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