Fig. 1: Demonstration of wireless magneto-ionics in CoN films using an experimental setup with horizontal configuration.

a Schematic illustration of the electrochemical cell and a simplified sketch depicting the induced poles formed and the voltage-controlled nitrogen ion motion at the film-electrolyte interface. The two edges of the bipolar magneto-ionic sample, indicated by blue dashed lines, correspond to the anodic (left) and cathodic (right) poles, whereas the blue dashed line depicted at the centre of the sample corresponds to an initial zero-charge position where the interfacial potential difference is zero with respect to the electrolyte. Note that, for clarity, the sketch depicts only the reactions at the cathodic pole (a correlated \({{{{{{\rm{I}}}}}}}^{-}\) oxidation to I₂ occurs simultaneously at the solution near the induced anode). b Schematics of the potential profile for the electrolyte and the distortion occurring when a conducting material is immersed in the electrolyte. The deviation from the original electrolyte profile corresponds to the induced poles, opposing the external field, at the extremes of the material. c Room-temperature hysteresis loops for the CoN films subject to an external driving voltage of 15 V for 5 min using the setup shown in a. The evolution of the saturation magnetization over time indicates the volatility of the magneto-ionic effect for such configuration.