Spin-dependent properties of magnetic III-V semiconductors

Spin-dependent properties of a new magnetic semiconductor based on a III-V compound, (Ga,Mn)As, are reviewed. It is now possible to prepare epitaxial thin films of an alloy between non-magnetic GaAs and magnetic ions such as Mn that exhibit ferromagnetism with a transition temperature as high as 110 K by low-temperature molecular beam epitaxy (< 300 degreesC). Exchange interactions between localized Mn spins and conduction carriers manifest themselves in a variety of transport properties, and from these one can determine the magnitude of the interaction. (Ga,Mn)As can readily be incorporated in the existing (Al,Ga)As/GaAs semiconductor heterostructures, allowing one to explore new fields in semiconductor physics and technology, where both semiconducting and magnetic properties play critical roles.