Planar Hall Effect in Epitaxial Fe Layers on GaAs(001) and GaAs(113)A Substrates

For ferromagnetic layers with in-plane magnetic fields, the longitudinal and transverse resistivities probe the magnetization orientation and its reversal via a spin-orbit-related resistance anisotropy. In the planar Hall effect, we found new contributions in Fe films on GaAs(001) and GaAs(113)A substrates, which cannot be understood within the conventionally used model of the resistance anisotropy. To understand its origin, we adopted a method to determine the orientation of the magnetization from magnetoresistance data. As a result, we were able to identify a symmetric fourfold and a twofold saturated asymmetric in-plane Hall effect for the Fe/GaAs(001) and Fe/GaAs(113)A systems, respectively. Since these new contributions almost perfectly compensate the planar Hall effect based on the resistance anisotropy, we argue about an intrinsic origin of the planar Hall effect in terms of scattering at spin textures within the Fe films.