Two-dimensional (2D) magnets with tunable ferromagnetic resonance (a phenomenon where the magnetization in a magnetic material resonates with an external electromagnetic field) and spin waves (fluctuation caused by the magnetic interaction between magnetic atoms) are gaining attention for energy-efficient electronics due to their lightweight and low-dimensional nature. Unlike bulky materials such as ferrites and metals, 2D magnets offer better integration with nanoscale devices, like magnetic insulators, and spintronic and magnetic tunnel junctions. However, their low Curie temperature (TC) and reliance on disruptive control methods (such as electrolyte gating, voltage tailoring, high pressure) have limited their use.

The team carried out the lithiation in an electrochemical cell with a CrI3-coated copper foil as the cathode, a lithium anode, and an electrolyte of lithium perchlorate dissolved in anhydrous propylene carbonate. By modulating the voltage applied to the cathode, lithium intercalation could be finely tuned, allowing for control of the material’s electronic, structural, and magnetic properties.