Longitudinal and transverse unidirectional magnetoresistances driven by interfacial spin-orbital scattering

The recent observation of the unidirectional spin Hall magnetoresistance (USMR) -- a longitudinal magnetoresistance that changes sign with the reversal of either the in-plane electric field or the magnetization -- in ferromagnetic and heavy metal bilayers has led to increased interest in the study of nonlinear magnetotransport effects. Here, we predict both longitudinal and transverse unidirectional magnetoresistances in magnetic layered structures, which do not rely on the spin Hall effect but instead arise from the concerted actions of interfacial Rashba spin-orbit coupling and spin-dependent scattering. We analyze the nonlinear magnetotransport using both a semiclassical Boltzmann equation approach and a full quantum mechanical approach and will discuss the dependence of the proposed effect on quantum coherence, interface property as well as the thicknesses of the layers.