About the book

The book contains a theory of and experimental data on the semiconducting compounds of transition and rare-earth elements. Peculiar to magnetic semiconductors is the extremely strong influence exercised by their magnetic properties on their electrical and optical properties, and vice versa, the conduction electrons can have a significant effect on the magnetic properties. For this reason magnetic semiconductors display a number of unique properties as compared to non-magnetic semiconductors and magnetic nonsemiconducting materials. For instance, their band-gap is strongly dependent on magnetization, and the type of magnetic ordering in them can be altered by varying charge carrier concentration. New types of carrier states are possible in magnetic semiconductors when the conduction electrons create a region of a normally unstable phase in the crystal (e.g. the ferromagnetic phase in an anti-ferromagnet) and then stabilize it by their autolocalization in it. Especially interesting is the manifestation of such a heterophase auto localization in degenerate semiconductors which results in magnetically-heterogeneous states of uniform crystals, and in the phase transitions of the insulator-metal type induced by a magnetic field or by temperature variations. The superposition of charge density and spin density waves is also possible in such semiconductors. At small charge carrier concentrations some magnetic semiconductors almost behave like ideal Heisenberg magnets, and their critical properties serve as test for the modern theory of phase transitions. Several general aspects of physics of magnetic phenomena (indirect exchange, singlet magnetism, etc.) and some aspects of the physics of semiconductors and materials exhibiting the insulator-metal phase transition are also dealt with in the book.