Enhancement of spin–orbit torque via interfacial hydrogen and oxygen ion manipulation

Abstract

We report a large enhancement of spin–orbit torque (SOT) in perpendicular Ta/CoFeB/MgO multilayers with interfacial H+ and O2– ion manipulations. By controlling both H+ and O2– ions at the CoFeB/MgO interface, the switching current density (Jc) is almost half of that for the single O2– ion manipulated sample. Through harmonic measurements, we have found that both dampinglike effective field HD and fieldlike effective field HF are increased for the H+ and O2– ion manipulated samples. Interfacial structural results indicate that the H+ and O2– ion manipulations modulate the interfacial chemistry at the CoFeB/MgO interface, which suppresses the spin reflection and improves the spin absorption in the CoFeB layer. Our results can effectively improve the SOT and provide an effective way to modulate SOT.