Ferromagnetic III-Mn-V semiconductors: basic issues and prospects for spintronic applications

Interest in the properties of ferromagnetic alloys of the type IIIi.1-XMnXV is primarily fueled by the promise which they hold of spin-electronic ("spintronic") applications. Although this promise is presently tempered by the fact that the Curie temperatures of III1-xMnxV alloys are still below 200K, progress in understanding the fundamental physics of these materials has been made on many fronts, which can in turn lead to breakthroughs toward high-temperature ferromagnetism in IIIi1-xMnxV alloys. In this paper we review the issues which determine the incorporation of Mn into the III-V lattice and of achieving high doping levels of the resulting material, both of which limit the Curie temperature. We then discuss mechanisms for controlling and manipulating the magnetic anisotropy of these materials, an issue that is of particular importance for the design of spin-injection-based devices; and we use our recent results on Ga1-xMnxAs films grown on vicinal (tilted) GaAs substrates as an illustration of the wide range of spin-based device opportunities that can be based on III1-xMnxV alloys as further progress is made in understanding and optimizing their properties.