凯发

In this talk, we will introduce our experimental observations of an exotic insulator: by bringing Bernal-stacked bilayer graphene into contact with a few-layered antiferromagnetic insulator CrOCl, the resulted vertical heterostructures can give rise to an extraordinarily robust ground state of insulator at the charge neutrality.

The consequential over-1-GOhm insulator can be readily suppressed by the vertical electrical field, in-plane electrical field, and effective doping, and the system recovers to a high mobility graphene with a sheet resistance of a few hundred Ohms. I-V curves as well as temperature- and magnetic field-dependences of conductance point such insulator to an excitonic insulating phase, which is attributed to the subtle coupling of graphene-CrOCl interface and the e-e interaction in the bilayer graphene.

Based on this correlated insulating state, both N-type and P-type doped transistors can be achieved by maintaining a fixed top gate (or bottom gate) and scanning the appropriate bottom gate (or top gate). These transistors exhibit a switching ratio of above 10^7 and possess strong robustness. Furthermore, by using two such CrOCl/BLG/hBN devices, we can obtain a graphene transistor inverter with a gain of approximately 1.2 at a temperature of 1.5 K and an input voltage of 0.2 V [1]. This represents a crucial step forward in the future electronic applications of graphene.

Reference:
[1] K. Yang, et al., Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene. Nature Communications 14, 2136 (2023).