Anomalous Hall effects in amorphous Ni74Mn24Pt2 film -: art. no. 134425

Hall resistivity and magnetic measurements for the amorphous Ni74Mn24Pt2 film have been carried out as a function of magnetic field up to 120 kOe in a wide temperature range. The anomalous Hall coefficient, R-s, the ordinary Hall coefficient R-0, the total hysteresis width of the Hall resistivity Delta H are deduced for several temperatures in the temperature range of 1.5-150 K. The Hall voltage was observed in the zero external fields at the temperature below T=10 K for both zero field cooling (ZFC) and field cooling (FC) cases. The Hall resistivity hysteresis curves become completely symmetric with respect to the field axis at the temperatures above 15 K where the unidirectional fields lost its rigidity All these anomalous effects have been explained in terms of asymmetric spin-orbit scattering of the conduction electron, which are polarized to the direction of the unidirectional exchange field. It is concluded that the surface becomes dominant at low temperatures. This assertion has been supported by the susceptibility measurements.