Twisted Kagome Bilayers: Higher-Order Magic Angles, Topological Flat Bands, and Sublattice Interference

TL;DR

This paper introduces a generalized continuum model for twisted bilayer kagome metals, revealing higher-order magic angles, topological flat bands, and the nuanced role of sublattice interference in moiré physics.

Contribution

It develops a new low-energy continuum model extending the Bistritzer-MacDonald approach to twisted kagome bilayers, uncovering higher-order magic angles and topological phenomena.

Findings

Identification of higher-order magic angles with flat bands

Twisting induces non-trivial topological properties

Sublattice interference effects are less prominent than in monolayer kagome

Abstract

We develop a low-energy continuum model to describe the moir\'{e} physics of heterostructures, which is a generalization of the celebrated Bistritzer-MacDonald (BM) method [R. Bistritzer and A. H. MacDonald, Proc. Natl. Acad. Sci. U.S.A. 108, 12233 (2011)]. We take as an example the moir\'{e} physics of electrons in twisted bilayer kagom\'{e} (TBK) metals near $1/3$ filling where monolayer Dirac cones lie. We demonstrate the emergence of higher-order magic angles where significant local band flattening occurs as a high-order Van Hove singularity emerges and show how twisting alone can induce non-trivial topology. We, furthermore, show that while sublattice interference effects are present, their role is not as prominent as in monolayer kagome.