Unconventional correlated insulator in CrOCl-interfaced Bernal bilayer graphene.

Yang, Kaining; Gao, Xiang; Wang, Yaning; Zhang, Tongyao; Gao, Yuchen; Lu, Xin; Zhang, Shihao; Liu, Jianpeng et al. · Nat Commun · 2023

basic_science · Level V

Where this comes from

Abstract

The realization of graphene gapped states with large on/off ratios over wide doping ranges remains challenging. Here, we investigate heterostructures based on Bernal-stacked bilayer graphene (BLG) atop few-layered CrOCl, exhibiting an over-1-GΩ-resistance insulating state in a widely accessible gate voltage range. The insulating state could be switched into a metallic state with an on/off ratio up to 10<sup>7</sup> by applying an in-plane electric field, heating, or gating. We tentatively associate the observed behavior to the formation of a surface state in CrOCl under vertical electric fields, promoting electron-electron (e-e) interactions in BLG via long-range Coulomb coupling. Consequently, at the charge neutrality point, a crossover from single particle insulating behavior to an unconventional correlated insulator is enabled, below an onset temperature. We demonstrate the application of the insulating state for the realization of a logic inverter operating at low temperatures. Our findings pave the way for future engineering of quantum electronic states based on interfacial charge coupling.