Magnetic semiconductors

Both semiconductors and magnetic materials exhibit interesting properties that can be used in electronic devices. A material that combines these properties, i.e., a magnetic semiconductor, could show interesting cross effects, such as a large magnetoresistance, or hysteresis and the associated memory phenomena introduced in the semiconductive properties. The discovery of ferromagnetic semiconductors (EuSe, CdCr2Se4, etc.) and the subsequent study of their properties has shown that a strong interaction between charge carriers and magnetic properties indeed exists. In this paper the available experimental information on cross effects between electric and magnetic properties is reviewed. The observed phenomena are discussed on the basis of a simple model with an exchange interaction between the charge carriers and the magnetic moments. Finally, the possibilities for observing the Gunn effect in magnetic semiconductors is discussed.