Spin-dependent CPP transport properties of semiconductive-oxide/ferromagnet multilayers

Abstract

The spin-dependent CPP (current perpendicular to plane) transport properties in semiconductive-oxide(MO x )/ferromagnet multilayers consisting of CoPt/Co/MO x /Co/MO x /Co/CoPt, where M=Ti, Sn, were investigated by magneto-transport measurement. The XRD patterns reveal that the structures of sputtered MO x films are amorphous or nanocrystalline. The MR ratio of a TiO x -based multilayer (0.43%) was much smaller than that of a SnO x -based one (2.0%) at T=77 K. As inferred from the shape of MR curves with a large saturation field above 4 kOe, suppressed MR change in the TiO x -based multilayer is caused by the interlayer diffusion of Co atoms into the TiO x layer. The same behavior was not observed in the SnO x -based one. The MR ratio was reduced by half on increasing t SnO x from 4 to 8 nm. This decrease can be ascribed to the scattering of the spin-polarized electron in the SnO x layer.