Electronic Structure, Local Moments and Transport in Fe_2VAl

TL;DR

This study uses density functional calculations to explore the electronic, magnetic, and transport properties of Fe_2VAl, revealing its semimetallic nature, local moments from Fe impurities, and potential spin-glass behavior.

Contribution

It provides a detailed theoretical analysis of Fe_2VAl's electronic structure and magnetic interactions, linking them to experimental phenomena and suggesting possible spin-glass behavior.

Findings

Fe_2VAl is a low carrier density semimetal with small Fermi surface pockets.

Fe impurities act as local magnetic moments on V sites.

The compound is stable against ferromagnetism, but local moments may lead to spin-glass behavior.

Abstract

Local spin density approximation calculations are used to elucidate electronic and magnetic properties of Heusler structure Fe_2VAl. The compound is found to be a low carrier density semimetal. The Fermi surface has small hole pockets derived from a triply degenerate Fe derived state at Gamma compensated by an V derived electron pocket at the X point. The ideal compound is found to be stable against ferromagnetism. Fe impurities on V sites, however, behave as local moments. Because of the separation of the hole and electron pockets the RKKY interaction between such local moments should be rapidly oscillating on the scale of its decay, leading to the likelihood of spin-glass behavior for moderate concentrations of Fe on V sites. These features are discussed in relation to experimental observations of an unusual insulating state in this compound.