Electronic Structure and Heavy Fermion Behavior in LiV_2O_4

TL;DR

This paper uses first-principles calculations to explore the electronic structure and magnetic properties of LiV₂O₄, revealing a complex interplay of bands that may explain its heavy fermion behavior through a Kondo-like mechanism.

Contribution

It provides a detailed electronic structure analysis of LiV₂O₄, proposing a novel scenario for its heavy fermion behavior involving weak scattering of conduction electrons by local moments within the same d-manifold.

Findings

Identification of a manifold of 12 bands near the Fermi energy from V t₂g states.

High density of states and magnetic instability associated with flat bands.

Proposed Kondo-like scenario for heavy fermion behavior in LiV₂O₄.

Abstract

First principles density functional calculations of the electronic and magnetic properties of spinel-structure LiV$_{2}$O$_{4}$ have been performed using the full potential linearized augmented planewave method. The calculations show that the electronic structure near the Fermi energy consists of a manifold of 12 bands derived from V $t_{2g}$ states, weakly hybridized with O p states. While the total width of this active manifold is approximately 2 eV, it may be roughly decomposed into two groups: high velocity bands and flatter bands, although these mix in density functional calculations. The flat bands, which are the more atomic-like lead to a high density of states and magnetic instability of local moment character. The value of the on-site exchange energy is sensitive to the exact exchange correlation parameterization used in the calculations, but is much larger than the interaction between neighboring spins, reflecting the weak coupling of the magnetic system with the high velocity bands. A scenario for the observed heavy fermion behavior is discussed in which conduction electrons in the dispersive bands are weakly scattered by local moments associated with strongly correlated electrons in the heavy bands.This is analogous to that in conventional Kondo type heavy fermions, but is unusual in that both the local moments and conduction electrons come from the same d-manifold.