Spin-orbit torque-induced magnetization switching in epitaxial Au/Fe4N bilayer films

Au/Fe₄N bilayer films have been grown by the plasma-assisted molecular beam epitaxy system. After an extraordinarily small charge current is applied to the samples, magnetization of the Fe₄N layer was reversed by spin-orbit torque. Analyses indicate that the magnetization reversal is realized via domain wall motion and it was confirmed by magnetic force microscopy measurements. By comparing the transport properties of the Au/Fe₄N bilayer film with those of control samples before and after using a pulse current to stimulate the films, contributions of the thermal effect and spin transfer torque induced by current that flows in the Fe₄N layer to the magnetization switching were analyzed and determined to be negligible. Kerr signals were observed simultaneously with applying a charge current to the samples at zero magnetic field, which could be explained by the spin Hall effect of the Au layer.