Diluted magnetic semiconductors

Diluted magnetic semiconductors (DMSs), i.e. semiconducting crystals whose lattice is made up in part of substitutional magnetic ions (e.g. Cd_1-xMn_xTe, Hg_1-xFe_x Se, Zn_1-xCo_xS), are reviewed. The focus is on materials of the type A_1-x^II Mn_xB ^VI, which are the most thoroughly understood. However, the similarities and differences between these materials and the A_1-x ^IIFe_xB^VI and A_1-^IICo_xB^VI systems are discussed wherever information on the latter system is available. The band structure of the materials, which determines their basic semiconducting properties, is examined. Special attention is given to exchange interactions between the magnetic ions themselves (the d -d interaction) and the interaction between the magnetic ions and band electrons (the sp-d interaction). Magnetic phenomena in DMS alloys are considered. Special attention is given to the physics of layered structures, such as quantum wells and superlattices, involving DMS materials. The prospects of device applications made possible by the properties of DMS alloys are assessed