<i>Electrostatic Control of Magnetism in a van der Waals Ferromagnetic Semiconductor</i>

Control of magnetism via electric fields is a long-standing exciting challenge of fundamental significance for future spintronic devices. Recent discovery of two-dimensional magnetism in van der Waals systems highlights their unique potential as a platform to probe the interplay between charge and magnetic ordering [1]. Here, we report the first observation of carrier-induced ferromagnetic order in heavily doped thin crystals of Cr₂Ge₂Te₆ (CGT) [2]. Upon degenerate electron doping, the CGT transistor exhibits clear hysteresis in the magnetoresistance at 200 K, far above the Curie temperature of undoped CGT (61 K). We find the magnetic easy-axis of doped CGT to lie within the plane of the crystal, which is in stark contrast to the out-of-plane easy-axis of the pristine material. We attribute these changes to emergence of the double-exchange interaction mediated by free carriers. This mechanism dominates over superexchange interaction, which is responsible for the ferromagnetic order in undoped CGT. Our findings reveal a unique role of the electric field in tailoring the magnetic anisotropy and leading exchange interaction in semiconducting 2D ferromagnets.

[1] Gibertini et al, Nat. Nanotechnol. 14, 408–419 (2019)
[2] Verzhbitskiy et al, Nat. Electron. 3, 460–465(2020)