Growth and characterization of insulating ferromagnetic semiconductor (Al,Fe)Sb

TL;DR

This study explores the growth, structure, and magnetic properties of Fe-doped (Al,Fe)Sb thin films, revealing ferromagnetism at low temperatures and potential for spintronic applications.

Contribution

It presents the first detailed characterization of (Al,Fe)Sb thin films grown by molecular beam epitaxy, demonstrating ferromagnetism up to 40 K and insights into phase separation effects.

Findings

(Al,Fe)Sb maintains zinc blende structure up to 10% Fe doping.

Ferromagnetism observed with a Curie temperature of 40 K at 10% Fe.

Higher Fe doping leads to phase separation and reduced mobility.

Abstract

We investigate the crystal structure, transport and magnetic properties of Fe-doped ferromagnetic semiconductor (Al1-x,Fex)Sb thin films up to x = 14% grown by molecular beam epitaxy. All the samples show p-type conduction at room temperature and insulating behavior at low temperature. The (Al1-x,Fex)Sb thin films with x lower or equal to 10% maintain the zinc blende crystal structure of the host material AlSb. The (Al1-x,Fex)Sb thin film with x = 10% shows intrinsic ferromagnetism with a Curie temperature (TC) of 40 K. In the (Al1-x,Fex)Sb thin film with x = 14%, a sudden drop of mobility and TC was observed, which may be due to microscopic phase separation. The observation of ferromagnetism in (Al,Fe)Sb paves the way to realize a spin-filtering tunnel barrier that is compatible with well-established III-V semiconductor devices.