Modulation of spin-orbit torque induced magnetization switching in Pt/CoFe through oxide interlayers

We investigate the spin–orbit torque (SOT) induced magnetization switching in the Pt/CoFe structure via inserting NiO or MgO interlayers. The effective spin Hall angles are enhanced by inserting a NiO layer and decreased by a MgO interlayer, through the harmonic Hall measurement. Both the MgO and NiO interlayers decrease the critical switching current and the minimum in-plane field required for completely switching, which is decreased down to about 50 Oe for a sample with MgO and 25 Oe for a sample with NiO. This originates from the reduction of the Dzyaloshinskii-Moriya interaction by inserting the oxide interlayers, which is confirmed by the Kerr images for the switching process. We confirm that the oxide interlayer is an efficient way to modify the SOT-induced magnetization switching and reveal the possibility of the SOT-induced switching for double MgO-based perpendicular magnetic tunneling junctions.