MAGNETORESISTANCE IN NI-PT MULTILAYERS WITH PERPENDICULAR AND INPLANEMAGNETIZATION

High resolution magnetoresistance (Delta rho/rho) measurements were ma de on a series of Ni-x-Pt-20 Angstrom samples. Other studies have show n the dominance of perpendicular spontaneous magnetization (M) for x < 17 Angstrom. For thick Ni-layer samples (M in-plane) our Angstrom rho /rho results show the usual Smitt anisotropy with respect to the angle magnetic field/electrical current, while for thin Ni-layer (M perpend icular) Delta rho/rho is always negative. In the intermediate case the coexistence of the mechanisms leads to an anomalous minimum in Delta rho/rho at low fields, when H parallel to I.