Ferromagnetic GaSb/Mn digital alloys

In order to realize spintronic devices in narrow-gap semiconductors, we have carried out studies on the well-known InAs/GaSb-based materials and structures. As a key component to such devices, GaSb/Mn digital alloys were successfully grown by molecular beam epitaxy. Good crystal quality was observed with transmission electron microscopy showing well-resolved Mn-containing layers and no evidence of 3D MnSb precipitates in as-grown samples. Ferromagnetism was observed in GaSb/Mn digital alloys with temperature-dependent hysteresis loops in magnetization up to 400 K (limited by the experimental setup). Magnetotransport studies were also carried out, both in the conventional Hall-bar configuration, and on gated Hall-bar structures. Both anomalous Hall effect and tunable ferromagnetism with applied gate bias were investigated. Annealing studies of the digital alloys reveal evidence of migration of Mn atoms at elevated temperatures.