Interfacial, electrical, and spin-injection properties of epitaxial $Co2MnGa$ grown on GaAs(100) Available to Purchase

The interfacial, electrical, and magnetic properties of the Heusler alloy $Co2MnGa$ grown epitaxially on GaAs(100) are presented with an emphasis on the use of this metal-semiconductor combination for a device that operates on the principles of spin-injection between the two materials. Through systematic growth optimization the stoichiometry in the bulk $Co2MnGa$ can be controlled to better than ±2%, although the interface is disordered and limits the spin-injection efficiency in a practical spintronic device irrespective of the half-metallic nature of the bulk metal. Molecular beam epitaxial growth was monitored in situ by reflection high energy electron diffraction and the bulk composition was measured ex situ with inductively coupled plasma optical emission spectroscopy. The $Co2MnGa$ $L21$ cubic structure is strained below a thickness of 20 nm on GaAs(100) but relaxed in films thicker than 20 nm. Electrical measurements on the $Co2MnGa$ reveal general characteristics of a disordered electron system with insulating behavior for layer thicknesses $<4nm$⁠. Thicker layers show a negative magnetoresistance with extraordinary Hall effect constants up to $30ΩT−1$⁠. Spin polarization transfer across the interface between $Co2MnGa$ and GaAs is approximately 6.4% at 5 K in the current of a GaAs $p-i-n$ diode even with compositional disorder at the interface.