Moir\'{e} Flat Bands of Twisted Few-layer Graphite

TL;DR

This paper introduces twisted few-layer graphite as a new moiré heterostructure with highly tunable flat band features, potential for multiband superconductivity, and topological properties, expanding the landscape of 2D material research.

Contribution

It reveals the rich and tunable flat band structures of tFL-graphite, highlighting their dependence on layer number and external electric fields, and proposes their potential for novel superconducting and topological phenomena.

Findings

Presence of coexisting flat and dispersive bands near the magic angle.

Electric field can induce isolated flat bands with nonzero valley Chern number.

tFL-graphite exhibits unique tunable moiré flat band structures.

Abstract

We report that the twisted few layer graphite (tFL-graphite) is a new family of moir\'{e} heterostructures (MHSs), which has richer and highly tunable moir\'{e} flat band structures entirely distinct from all the known MHSs. A tFL-graphite is composed of two few-layer graphite (Bernal stacked multilayer graphene), which are stacked on each other with a small twisted angle. The moir\'{e} band structure of the tFL-graphite strongly depends on the layer number of its composed two van der Waals layers. Near the magic angle, a tFL-graphite always has two nearly flat bands coexisting with a few pairs of narrowed dispersive (parabolic or linear) bands at the Fermi level, thus, enhances the DOS at $E_F$. This coexistence property may also enhance the possible superconductivity as been demonstrated in other multiband superconductivity systems. Therefore, we expect strong multiband correlation effects in tFL-graphite. Meanwhile, a proper perpendicular electric field can induce several isolated nearly flat bands with nonzero valley Chern number in some simple tFL-graphites, indicating that tFL-graphite is also a novel topological flat band system.