Structure and magnetism in Fe-doped FeVSb and epitaxial Fe/FeVSb nanocomposite films

TL;DR

This study synthesizes Fe-doped FeVSb films and Fe/FeVSb nanocomposites, revealing weak ferromagnetism at low temperatures and interface-induced magnetism, with potential implications for spintronics and thermoelectrics.

Contribution

It demonstrates the epitaxial growth and magnetic properties of Fe-doped FeVSb and nanocomposite films, highlighting interface-induced magnetism and phase behavior.

Findings

Weak ferromagnetism at ~5K in dilute Fe doping

Precipitation of Fe nanostructures at higher Fe content

Proximity-induced magnetism at Fe/FeVSb interfaces around 20K

Abstract

The combination of ferromagnetism and semiconducting behavior offers an avenue for realizing novel spintronics and spin-enhanced thermoelectrics. Here we demonstrate the synthesis of doped and nanocomposite half Heusler Fe$_{1+x}$VSb films by molecular beam epitaxy. For dilute excess Fe ($x < 0.1$), we observe a decrease in the Hall electron concentration and no secondary phases in X-ray diffraction, consistent with Fe doping into FeVSb. Magnetotransport measurements suggest weak ferromagnetism that onsets at a temperature of $T_{c} \approx$ 5K. For higher Fe content ($x > 0.1$), ferromagnetic Fe nanostructures precipitate from the semiconducting FeVSb matrix. The Fe/FeVSb interfaces are epitaxial, as observed by transmission electron microscopy and X-ray diffraction. Magnetotransport measurements suggest proximity-induced magnetism in the FeVSb, from the Fe/FeVSb interfaces, at an onset temperature of $T_{c} \approx$ 20K.