Entangled Moire Chern Insulator in Rhombohedral Graphene

TL;DR

This paper reports the discovery of an intrinsic Chern insulator with C=1 at moire filling v=2 in rhombohedral octalayer graphene, revealing new topological phases driven by band entanglement and strong interactions.

Contribution

It demonstrates the existence of a C=1 Chern insulator at v=2 in rhombohedral graphene, supported by Hartree-Fock calculations, extending the topological phase diagram of moire systems.

Findings

Observation of C=1 Chern insulator at v=2 in R8G/hBN moire superlattice

Identification of band entanglement as origin of the topological state

Extension of topological phase diagram for rhombohedral multilayer graphene

Abstract

Graphene-based moire superlattices exhibit novel quantum phenomena driven by pronounced interactions, leading to topological corrected states like orbital Chern insulators exhibiting quantum anomalous Hall effect (QAHE). Typically, intrinsic Chern insulators are stabilized at odd moir\'e fillings, as even fillings often result in valley-balanced, topologically trivial states at zero magnetic field. In our work, we report the observation of an intrinsic Chern insulator with C = 1 state at moire filling v = 2 in rhombohedral octalayer graphene (R8G)/hBN moire superlattice. Observing such Chern insulators in particular with C = 1 at v = 2 is intriguing, as each moir\'e band carries Chern number C = 1 or -1. We further demonstrate such a state can originate from the entanglement between the low-energy moire flat bands and high-energy remote bands according to the Hartree-Fock calculation. Our findings extend the known topological phase diagram of rhombohedral multilayer graphene (RMG) moire systems and establish this platform as highly promising for investigating strong electron correlations and multiband hybridized transport.