Controlling Magneto-Ionics by Defect Engineering Through Light Ion Implantation

Magneto-ionics relies on the voltage-driven transport of ions to modify magnetic properties. As a diffusion-controlled mechanism, defects play a central role in determining ion motion and, hence, magneto-ionic response. Here, the potential of ion implantation is exploited to engineer depth-resolved defect type and density with the aim to control the magneto-ionic behavior of CoO thin films. It is demonstrated that through a single implantation process of light ions (He) at 5 keV, the magneto-ionic response of a nanostructured 50 nm thick CoO film, in terms of rate and amount of induced magnetization, at short-, mid-, and long-term voltage actuation, can be controlled by varying the generated collisional damage through the ion fluence. These results constitute a proof-of-principle that paves the way to further use ion implantation (tuning the ion nature, energy, fluence, target temperature, or using multiple implantations) to enhance performance in magneto-ionic systems, with implications in ionic-based devices.