ABSTRACT
Material templates used in spintronics include various metallic magnetic materials that show a direct magnetoresistive effect or metallic junctions with tunneling magnetoresistance. Also, nonmagnetic semiconductors are recognized as a material template for spintronic devices since the spin-polarized electrons injected from metallic ferromagnetic contact may have a long spin lifetime enabling spin transfer to another ferromagnetic electrode where the spin information can be read out. The conductivity mismatch between a ferromagnetic metal contact and a semiconductor active region degrades the efficiency of spin injection. There are two basic ways to avoid the conductivity mismatch: One is to use tunnel contacts, another is to replace ferromagnetic metals with semiconductor alloys containing transition-metal atoms such as Fe, Mn, and Co providing they show room-temperature ferromagnetism [1, 2]. Ferromagnetic semiconductors would benefit device performance as the all-semiconductor structure can be grown lattice matched to the other part of the device, reducing the defect density, and increasing the lifetime of non-equilibrium carriers and the spin relaxation time.
