Voltage-Induced ON Switching of Magnetism in Ordered Arrays of Non-Ferrimagnetic Nanoporous Iron Oxide Microdisks

Tailoring the magnetic properties of ordered arrays of patterned structures usually requires stringent control of their size, pitch, microstructure, and composition. Here, a fundamentally different approach to manipulate the magnetic behavior of lithographed microdisks, based on the application of electrical voltage, is demonstrated. First, highly porous iron oxide films with virtually no magnetic response (OFF state) are grown by sol–gel chemistry. Subsequently, arrays of microdisks (8 µm in diameter) are obtained combining lithography with wet chemical etching processes. Electrolyte-gating (with an anhydrous electrolyte) is then employed to induce a tunable (i.e., “on-demand”) ferromagnetic response in these disks (OFF–ON switching of magnetism) at room temperature. The changes in magnetic properties are attributed to magnetoelectrically-driven oxygen ion migration, which is enhanced due to nanoporosity.