Reversible and Irreversible Voltage Manipulation of Interfacial Magnetic Anisotropy in Pt / Co /Oxide Multilayers

The perpendicular magnetic anisotropy at the Co-oxide interface in Pt/Co/MOx (MOx=MgOx, AlOx, TbOx) is modified by an electric field using a 10-nm-thick ZrO2 as a solid electrolyte. The large voltage-driven modification of the interfacial magnetic anisotropy and the nonvolatility of the effect is explained in terms of the migration of oxygen ions toward or away from the Co/MOx interface. While the effect is reversible in Pt/Co/AlOx and Pt/Co/TbOx, where the Co layer can be oxidized or reduced, in Pt/Co/MgOx the effect is found to be irreversible. We propose that these differences may be related to the different nature of the ionic conduction within the MOx layers.