Family of High-Chern-Number Orbital Magnets in Twisted Rhombohedral Graphene

TL;DR

This paper reports the discovery of a family of high-Chern-number orbital magnets in twisted rhombohedral graphene, demonstrating tunable topological states with potential for dissipationless transport.

Contribution

The study introduces a new class of high-Chern-number orbital magnets in twisted graphene, combining experimental observations with theoretical support and demonstrating control over Chern number via layer and valley polarization.

Findings

Observation of anomalous Hall effects at specific electron fillings

Verification of topological hierarchy C = n through measurements

Electrical and magnetic switching of high-Chern-number states

Abstract

Realizing Chern insulators with Chern numbers greater than one remains a major goal in quantum materials research. Such platforms promise multichannel dissipationless chiral transport and access to correlated phases beyond the conventional C = 1 paradigm. Here, we discover a family of high-Chern-number orbital magnets in twisted monolayer-multilayer rhombohedral graphene, denoted (1+n) with n = 3, 4, and 5. Magnetotransport measurements show pronounced anomalous Hall effects at one and three electrons per moir\'e unit cell when they are polarized away from the moir\'e interface. Across the (1+n) systems, we observe a clear topological hierarchy C = n, revealed by the St\v{r}eda trajectories and the quantized Hall resistance. Our experimental observations are supported by self-consistent mean-field calculations. Moreover, we realize both electrical and magnetic switching of the high-Chern-number states by flipping the valley polarization. Together, these results establish a tunable hierarchy of orbital Chern magnets in twisted rhombohedral graphene, offering systematic control of Chern number and topology through layer engineering in pristine graphene moir\'e systems.