Flat bands for electrons in rhombohedral graphene multilayers with a twin boundary

TL;DR

This paper investigates the topological and electronic properties of rhombohedral graphite with a twin boundary, revealing conditions for localized flat bands that could host strongly correlated electron states.

Contribution

It develops an effective 4-band model incorporating SWMcC parameters to analyze surface and interface bands in rhombohedral graphite with a twin boundary.

Findings

Conditions for band localization at the twin boundary.

Protection of flat bands from disorder.

Potential for strongly correlated states due to high density of states.

Abstract

Topologically protected flat surface bands make thin films of rhombohedral graphite an appealing platform for searching for strongly correlated states of 2D electrons. In this work, we study rhombohedral graphite with a twin boundary stacking fault and analyse the semimetallic and topological properties of low-energy bands localised at the surfaces and at the twinned interface. We derive an effective 4-band low energy model, where we implement the full set of Slonczewski-Weiss-McClure (SWMcC) parameters, and find the conditions for the bands to be localised at the twin boundary, protected from the environment-induced disorder. This protection together with a high density of states at the charge neutrality point, in some cases -- due to a Lifshitz transition, makes this system a promising candidate for hosting strongly-correlated effects.