The semiconductor-to-ferromagnetic-metal transition in FeSb2

TL;DR

This paper investigates FeSb2 as a nearly ferromagnetic small gap semiconductor, demonstrating a transition to a ferromagnetic metal under an external magnetic field, similar to FeSi, using computational methods.

Contribution

It reveals the magnetic and electronic degeneracy in FeSb2 using LDA+U calculations, proposing a transition mechanism akin to FeSi and FeSi1-xGex alloys.

Findings

FeSb2 is a nearly ferromagnetic small gap semiconductor.

Magnetic and semiconducting states are energetically degenerate at U=2.6 eV.

External magnetic fields can induce a transition to a ferromagnetic metal.

Abstract

We propose FeSb2 to be a nearly ferromagnetic small gap semiconductor, hence a direct analog of FeSi. We find that despite different compositions and crystal structures, in the local density approximation with on-site Coulomb repulsion correction (LDA+U) method magnetic and semiconducting solutions for U=2.6 eV are energetically degenerate similar to the case of FeSi. For both FeSb2 and FeSi (FeSi1-xGex alloys) the underlying transition mechanism allows one to switch from a small gap semiconductor to a ferromagnetic metal with magnetic moment 1 muB per Fe ion with external magnetic field.