Experimental approval of the extended flat bands and gapped subbands in rhombohedral multilayer graphene

TL;DR

This study provides the first experimental evidence of extended flat bands and gapped subbands in ABC-stacked multilayer graphene, revealing unique electronic properties and potential for strongly correlated states.

Contribution

It introduces a magneto-optical method to identify ABC stacking and demonstrates the existence of dispersionless bands in multilayer graphene with over 17 layers.

Findings

Identification of ABC stacking via Raman response

Observation of flat bands near the Fermi level

Evidence of gapped subbands in multilayer graphene

Abstract

Graphene layers are known to stack in two stable configurations, namely ABA or ABC stacking, with drastically distinct electronic properties. Unlike the ABA stacking, little has been done to experimentally investigate the electronic properties of ABC graphene multilayers. Here, we report the first magneto optical study of a large ABC domain in a graphene multilayers flake, with ABC sequences exceeding 17 graphene sheets. The ABC-stacked multilayers can be fingerprinted with a characteristic electronic Raman scattering response, which persists even at room temperatures. Tracing the magnetic field evolution of the inter Landau level excitations from this domain gives strong evidence to the existence of a dispersionless electronic band near the Fermi level, characteristic of such stacking. Our findings present a simple yet powerful approach to probe ABC stacking in graphene multilayer flakes, where this highly degenerated band appears as an appealing candidate to host strongly correlated states.