FIELD-DEPENDENCE OF THE ANOMALOUS HALL-EFFECT COEFFICIENT OF GRANULARALLOYS WITH GIANT MAGNETORESISTANCE

It is shown theoretically that the anomalous Hall effect (AHE) coeffic ient R-s of magnetic granular alloys exhibiting giant magnetoresistanc e (GMR) depends strongly and, in the general case, nonmonotonically on the magnetic field as a result of the effect of the field on the char acter of the charge-carrier scattering and the AHE. The experimental d ata, presented by H. Sate, H. Hemmi, Y. Kobayashi et al., J. Appl. Phy s. 76, 6919 (1994), on the field dependence R-s(H) in Co-Ag granular a lloys at low temperatures are explained. The presence of a maximum in the field dependence /R-s(H)/ in annealed Co-Ag alloys attests to the fact that skew scattering plays a dominant role in the formation of th e AHE and that the main carriers of the AHE in these alloys are states whose spin polarization is directed oppositely to the magnetization. The presence of a minimum in this dependence for unannealed samples in dicates nonuniformity of the granule size distribution. (C) 1997 Ameri can Institute of Physics.