In situ study of oxygen and Mg effects on current-induced magnetization switching in Pt/Co bilayers in ultrahigh vacuum

We report on an in situ study of oxygen exposure and Mg dusting effects on current-induced magnetization switching in Pt/Co bilayers via controlled oxygen exposure, Co and Mg deposition, and electrical measurements in ultrahigh vacuum. We show that the oxygen exposure and Mg dusting induce changes in saturation magnetization, effective magnetic anisotropy, spin-orbit torque, and switching current density. From the correlation between these parameters and the switching current density for current-induced switching, we found that the reduction in switching current density by oxygen exposure is caused by the combined effect of enhancement in spin-orbit torque and lowering of the switching energy barrier required for incoherent switching with the latter playing a dominant role in large samples.