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(tFe4N ≤ 6 nm)/MgO(sub)structures were investigated. Current-driven anomalous Hall resistivity ρAHE changes appear due to SOT. Moreover, sign reversal of Hall resistivity ρxy 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 ρxy occurs.