III-V-Based Ferromagnetic Semiconductors

III-V compound semiconductors such as GaAs and InAs alloyed with Mn exhibit ferromagnetism. The magnetic, electrical, and optical properties of ferromagnetic III-V semiconductors are first compiled along with the way to prepare the epitaxial films and the effect of postgrowth annealing. Theories available to explain the magnetism in these alloys are then presented. Because the ferromagnetic semiconductors are compatible with epitaxial III-V heterostructures, a number of device structures have been examined and shown to reveal a wide variety of phenomena that either cannot be realized or are very difficult to observe in ferromagnetic metal structures. The unique properties revealed by ferromagnetic semiconductor structures, ranging from reversible electric field control of ferromagnetic phase transition to generating velocity versus current-density curves of current-induced domain wall motion, are then reviewed. The prospect of realizing high-transition temperature is discussed in the last section.