Gate-controlled magnetic transitions in Fe₃GeTe₂ with lithium ion conducting glass substrate

Since the discovery of magnetism in two dimensions, effective manipulation of magnetism in van der Waals magnets has always been a crucial goal. Ionic gating is a promising method for such manipulation, yet devices gated with conventional ionic liquid may have some restrictions in applications due to the liquid nature of the gate dielectric. Lithium-ion conducting glass-ceramics (LICGC), a solid Li⁺ electrolyte, could be used as a substrate while simultaneously acts as a promising substitute for ionic liquid. Here we demonstrate that the ferromagnetism of Fe₃GeTe₂ (FGT) could be modulated via LICGC. By applying a voltage between FGT and the back side of LICGC substrate, Li⁺ doping occurs and causes the decrease of the coercive field (H_c) and ferromagnetic transition temperature (T_c) in FGT nanoflakes. A modulation efficiency for H_c of up to ～ 24.6% under V_g = 3.5 V at T =100 K is achieved. Our results provide another method to construct electrically-controlled magnetoelectronics, with potential applications in future information technology.