Spin orbit torque effect in ultrathin collinear and noncollinear Ir-Mn alloys

Abstract

Due to the presence of robust spin-sublattices, which have a low susceptibility to external magnetic field, spin current induced torques play a key role in antiferromagnetic-spintronic device implementations. Since the torque-efficiency is highly dependent on the angle between the spin polarization and the local moments, the noncollinear antiferromagnet IrMn3 with its well-defined local moment orientations dictated by the kagome lattice presents a unique prototypical materials system for such studies in antiferromagnets. In this work, we have investigated the optimum substrate choice and deposition conditions of (001) oriented IrMn3 in addition to spin-orbit torque effects due to a spin current from a positive (or negative) spin Hall angle neighboring Pt (or W) layer. Comparison with the collinear Ir20Mn80/Pt bilayers clarifies the contribution to the current induced resistance change from the triangular spin structure of IrMn3. Our study enables the assessment of the effectiveness of the spin-orbit torque induced manipulation of the Neel vector in noncollinear antiferromagnetic systems.