Robust chiral spin transport in the antiferromagnetic iron oxide/heavy metal bilayers

Abstract

We have observed robust chiral spin torques and non-reciprocal charge transport behaviors in the α-Fe2O3/Pt bilayers through a combination of magnetic field and current-dependent second longitudinal harmonic resistance measurements. The interfacial Dzyaloshinskii–Moriya interaction induced magnetic chirality has been predicted to account for the sign reversal characteristic of the second longitudinal harmonic resistance with increasing the current amplitude. A physical model that considers the chirality dependence of both the asymmetric scattering and the giant Rashba spin–orbit coupling has been set up to uncover the microscopic interactions between charge, spin, and magnetic chirality. Our comprehensive approach leverages the semiclassical Boltzmann theory to validate the consistency between this model and our experimental findings. Through our investigation, we have established the pivotal role of interfacial magnetic chirality in determining both charge and spin transport behaviors within antiferromagnetic insulator/heavy metal bilayer systems. Our work not only enhances the comprehension of spin–orbit torques and non-reciprocal charge transport but also contributes to the broader understanding of these phenomena. The outcomes of this study have broader implications for the advancement of spintronics and related fields.