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

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 Fe1+xVSb 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 Tc ≈ 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 Tc ≈ 20K.