Twisted Kagome Bilayers: Higher-Order Magic Angles, Topological Flat Bands, and Sublattice Interference
David T. S. Perkins, Joseph J. Betouras
TLDR
This paper introduces a generalized moiré physics model for twisted kagome bilayers, revealing higher-order magic angles and topological flat bands.
Key contributions
- Develops a generalized low-energy continuum model for moiré heterostructures.
- Demonstrates higher-order magic angles with significant band flattening in twisted kagome bilayers.
- Shows that twisting alone can induce non-trivial topology in these systems.
- Notes sublattice interference effects are present but less prominent than in monolayer kagome.
Why it matters
This research extends the understanding of moiré physics beyond traditional models, specifically for twisted kagome metals. It uncovers new phenomena like higher-order magic angles and topology induced by twisting, which could lead to novel electronic properties. This work opens avenues for designing advanced quantum materials.
Original Abstract
We develop a low-energy continuum model to describe the moiré 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 moiré physics of electrons in twisted bilayer kagomé (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.
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