Electrochemical and in situ magnetic study of iron/iron oxide films oxidized and reduced in KOH solution for magneto-ionic switching

An electrochemical and in situ magnetic study is conducted to identify key parameters for room-temperature electrochemical (magneto-ionic) switching of magnetism by repeated oxidation and reduction of iron species in aqueous KOH. Potentiodynamic routines allow to distinguish the reaction potentials and, in contrast to measurements on bulk Fe electrodes, uncover the importance of dissolution processes in thin film geometry. The pH of the solution affects both dissolution and reduction to metallic iron. The magnetic properties strongly depend on the applied oxidation and reduction potentials. Large magnetic changes are obtained when switching between the potential of reduction to metallic iron and intermediate oxidation potentials, revealing an influence of the structure of the oxide layer.