Hall effect and magnetoresistance in p-type ferromagnetic semiconductors

Recent works aiming at understanding magnetotransport phenomena in ferromagnetic III-V and II-VI semiconductors are described. A theory of the anomalous Hall effect in p-type magnetic semiconductors is discussed, and the relative role of side-jump and skew-scattering mechanisms assessed for (Ga,Mn)As and (ZnMn)Te. It is emphasized that magnetotransport studies of ferromagnetic semiconductors in high magnetic fields make it possible to separate the contributions of the ordinary and anomalous Hall effects, to evaluate the role of the spins in carrier scattering and localization as well as to determine the participation ratio of the ferromagnetic phase near the metal-insulator transition. A sizable negative magnetoresistance in the regime of strong magnetic fields is assigned to the weak localization effect.