Perpendicular magnetization in Fe/Ni bilayers on GaAS(001)

Following the concept of spin-injection into a semiconductor-based device, a ferromagnetic element (like a GMR multilayer structure) can be used as a spin filter. A high spin-polarization of the electrons can be realized by t he preparation of a monocrystalline multilayer structure consisting of ultr athin films of a high magnetic polarization. In the case of ultrathin films , the manipulation of the easy-axis of magnetization is possible, by changi ng the anisotropy terms contributing to the effective anisotropy of the str ucture. We report on the structural and magnetic properties of Ni/Fe and Fe /Ni bilayers epitaxially grown on GaAs(0 0 1). By a proper choice of Fe and Ni sequences (Fe/Ni/GaAs) and their thickness (up to 3 ML of Fe on the top of Ni), the rotation of magnetization from the in-plane to the out-of-plan e direction was achieved. (C) 2001 Elsevier Science B.V. All rights reserve d.