Tunable high-Chern-number Chern insulators in rhombohedral tetralayer graphene/hBN moir\'e superlattices

TL;DR

This study reveals highly tunable high-Chern-number Chern insulators in rhombohedral tetralayer graphene/hBN moiré superlattices, demonstrating their dependence on moiré wavelength, electric, and magnetic fields.

Contribution

It reports the experimental discovery of multiple high-Chern-number Chern insulators with tunable properties in RTG/hBN moiré superlattices, including new symmetry-broken states.

Findings

Observation of C = -4 Chern insulator at v = -1

Discovery of symmetry-broken states with C = +3, ±2, ±1 at fractional fillings

High tunability of topological states via moiré wavelength, electric, and magnetic fields

Abstract

Moir\'e superlattices based on rhombohedral multilayer graphene have emerged as a highly tunable platform for engineering correlated topological phases. Here, we systematically investigate the transport properties of the hole-doped side in rhombohedral tetralayer graphene/ hexagonal boron nitride (hBN) moir\'e superlattices across a range of twist angles and alignment orientations. Notably, we observed multiple high-Chern-number Chern insulators, including the previously reported integer Chern insulator with Chern number C = -4 at moir\'e filling factor v = -1 and newly discovered symmetry-broken Chern insulating states with C = +3, $\pm$2, $\pm$1 at fractional moir\'e fillings of v = -2.5 or -2.6. These Chern insulating states emerge in both hBN alignment, but exhibit a sensitive moir\'e wavelength dependence. Our findings demonstrate the exceptional tunability of these high-Chern-number states via moir\'e wavelength, displacement electric field and external magnetic field, underscoring the distinct topological landscape realized in hole-doped RTG/hBN moir\'e superlattices.