Magneto-transport anisotropy in epitaxially grown hybrid MnAs/GaAs multilayer

Using molecular-beam epitaxy, we grew a MnAs/GaAs multilayer on a GaAs(100) substrate and compared its magneto-transport characteristics to those of a single-layer MnAs thin film. The crystal orientation of the MnAs layers in both samples was type-B. M-H measurements revealed two-fold symmetric magnetic anisotropy on the surface with the easy and hard direction of magnetization. When the current flowed along the hard direction, the MnAs/GaAs multilayer exhibited negative magnetoresistance below Curie temperature; when the current flowed along the easy direction, it turned positive. We suggest that this peculiar anisotropic magneto-transport behavior in the multilayer originated from two-dimensional carrier confinement and spin-orbit coupling.