Ionic liquid gating control of magnetism of a Co film

Ionic liquid gating has emerged as an attractive means of manipulating the magnetic properties of materials. Here, we report ionic liquid gating modulating the ferromagnetism of a Co film. A weak and strong saturation magnetization can be reversibly obtained by applying a negative voltage and a positive one, respectively. The modulation may be related with the oxidization and reduction of Co. Negative (or positive) gating voltages drive the oxygen ions to inject into (or extract from) Co layer of the sample, which oxidizes (or reduces) Co. These gating processes are reversible. Moreover, the magnetism of the gated states is considerably stable. It is a significant step towards designing low-power electric-controlling magnetic devices in future.