Electrical Control of a Layered Ferromagnetic Semiconductor

Recent discoveries of gate-tunable magnetism in ferromagnetic two-dimensional materials such as CrI₃ and Fe₃GeTe₂ highlight their unique potential for novel spintronics. We recently showed that degenerately electron-doped Cr₂Ge₂Te₆ (CGT), a van der Waals ferromagnetic semiconductor, exhibits remarkably enhanced Curie temperature and unusual rotation of its easy axis [1]. This phenomenon is also observed in Na-intercalated CGT using ferromagnetic resonance spectroscopy, revealing that heavy electron doping of the host is responsible for the observed changes in magnetic anisotropy. We further investigate the effect of strong surface electric field in inducing spin-orbit torque in ion-gated CGT. By monitoring second harmonic signals of longitudinal and transverse magnetoresistance at various external field orientations, we show that conduction electron spins act on the magnetic moment within the same material. We will further discuss our exploration of magnetism in other emerging van der Waals materials such as NbFeTe₂ and magnetically doped transition metal dichalcogenides.<br/><br/>[1] I. Verzhbitskiy, et al. Nat. Electron, 3, 460 (2020).