Flat Bands for Electrons in Rhombohedral Graphene Multilayers with a Twin Boundary

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, rhombohedral graphite is studied with a twin boundary stacking fault and the semimetallic and topological properties of low-energy bands, localized at the surfaces and at the twinned interface, are analyzed. An effective 4-band low energy model is derived, where the full set of Slonczewski-Weiss-McClure (SWMcC) parameters is implemented, and the conditions for the bands are found to be localized 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.