Quantum Hall phase in graphene engineered by interfacial charge coupling

TL;DR

This paper reports the discovery of an unusual quantum Hall effect in graphene interfaced with an anti-ferromagnetic insulator, showing unique Landau level behavior and potential for quantum electronic applications.

Contribution

It demonstrates a novel quantum Hall phase in graphene influenced by interfacial charge coupling with CrOCl, revealing new controllable quantum states at elevated temperatures.

Findings

Landau levels remain intact at negative filling fractions

Quantum Hall phase appears at zero magnetic field

Quantum states persist up to 100 K

Abstract

Quantum Hall effect (QHE), the ground to construct modern conceptual electronic systems with emerging physics, is often much influenced by the interplay between the host two-dimensional electron gases and the substrate, sometimes predicted to exhibit exotic topological states. Yet the understanding of the underlying physics and the controllable engineering of this paradigm of interaction remain challenging. Here we demonstrate the observation of an unusual QHE, which differs markedly from the known picture, in graphene samples in contact with an anti-ferromagnetic insulator CrOCl equipped with dual gates. Owing to the peculiar interfacial coupling, Landau levels in monolayer graphene remain intact at negative filling fractions, but largely deviated for the positive gate-doping range. The latter QHE phase even presents in the limit of zero magnetic field, with the consequential Landau quantization following a parabolic relation between the displacement field $D$ and the magnetic field $B$. This characteristic prevails up to 100 K in a sufficiently wide effective doping range from 0 to 10$^{13}$ cm$^{-2}$. Our findings thus open up new routes for manipulating the quantum electronic states, which may find applications in such as quantum metrology.