Demonstrating Current-Driven Anomalous Hall Resistivity in Epitaxial Pt(3 nm)/Fe4N(≤6 nm)/MgO Heterostructures toward Spintronic Devices

Current-induced spin–orbit torque (SOT) in heavy metal/ferromagnets can be used to manipulate the magnetization and electronic transport properties for logic and memory operations. Significantly, Fe₄N shows an in-plane magnetic anisotropy at larger thicknesses but enters a noncollinear magnetic phase at suitably nanoscale thicknesses. Here, the electronic transport properties of Pt(3 nm)/Fe₄N(t_Fe4N ≤ 6 nm)/MgO(sub)structures were investigated. Current-driven anomalous Hall resistivity ρ_AHE changes appear due to SOT. Moreover, sign reversal of Hall resistivity ρ_xy occurs due to the competition between the magnetic proximity effect and inverse spin Hall effect. A model based on the above contributions was built to demonstrate how torque changes with increasing charge current and why sign reversal of ρ_xy occurs.