Magnetic I mpurity In Narrow-Gap Semiconductors t

Lately IV-VI semiconductors with a narrow band-gap and with a number of free carriers have become the object of great concern such as about the band structure and phase transition associated with a softening of the transverse optical phonon. In addition, these materials have proved to be a good host matrix in the study of the effect of the magnetic impurities on various properties--magnetic properties, electron paramagnetic resonance, and transport proper-ties of the carriers, on which we have reviewed in this article. These phenom-ena are mostly understood in terms of the s-d exchange interaction between the localized magnetic impurities and the conduction carriers in much the same way as the magnetic dilute alloys (metals). 1. Introductin Although a clear definition is not given, the semiconductors that have a relatively narrow band-gap (Eg~10-leV) and involve a large number of conduction carriers are usually called as the narrow-gap semiconductors.l-a) These include III-V semi-conductors such as InSb, II-VI semiconductors like Cdl-xHgx Te, and IV-VI semicon-ductors as listed in Table I with which we are here concerned. In general IV-V