Electrical Tracking of the Mott Insulating Kitaev Magnet using Graphene/α-RuCl₃ Heterostructure

Electrical signatures for quantum magnetic phases of α-RuCl₃ sensed by an adjacent graphene field-effect transistor (FET) are reported. The gate-voltage dependence of the graphene FET reveals p-type doping beneath α-RuCl₃ caused by the charge transfer due to the work function difference. Furthermore, the gate-voltage hysteresis exhibits a marked change in the transport behavior with the temperature variation. The high-T simple paramagnetic phase and the low-T zigzag antiferromagnetic phase of α-RuCl₃ exhibit negligible hysteresis. In sharp contrast, a huge hysteresis of the graphene FET at intermediate temperatures is observed. The possibility that the observed conductance hysteresis is associated with the intriguing continuum excitations of the thermally induced Kitaev paramagnet state is discussed. The results show that the proximity effect-based electric approach can be utilized for investigating charge-neutral quasiparticles in quantum magnetic insulators.