Topological classification for chiral symmetry with non-equal sublattices

Fuente: arXiv
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Autori principali: Dai, J. X., Zhao, Y. X.
Natura: Preprint
Pubblicazione: 2024
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author Dai, J. X.
Zhao, Y. X.
author_facet Dai, J. X.
Zhao, Y. X.
contents Chiral symmetry on bipartite lattices with different numbers of $A$-sites and $B$-sites is exceptional in condensed matter, as it gives rise to zero-energy flat bands. Crystalline systems featuring chiral symmetry with non-equal sublattices include Lieb lattices, dice lattices, and particularly Moiré systems, where interaction converts the flat bands into fascinating many-body phases. In this work, we present a comprehensive classification theory for chiral symmetry with non-equal sublattices. First, we identify the classifying spaces as Stiefel manifolds and derive the topological classification table. Then, we extend the symmetry by taking $\mathcal{PT}$ symmetry into account, and ultimately obtain three symmetry classes corresponding to complex, real, and quaternionic Stiefel manifolds, respectively. Finally, we apply our theory to clarify the topological invariant for $\mathcal{PT}$-invariant Moiré systems and construct physical models with Lieb and dice lattice structures to demonstrate our theory. Our work establishes the theoretical foundation of topological phases protected by chiral symmetries with non-equal sublattices.
format Preprint
id arxiv_https___arxiv_org_abs_2405_16001
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Topological classification for chiral symmetry with non-equal sublattices
Dai, J. X.
Zhao, Y. X.
Mesoscale and Nanoscale Physics
Chiral symmetry on bipartite lattices with different numbers of $A$-sites and $B$-sites is exceptional in condensed matter, as it gives rise to zero-energy flat bands. Crystalline systems featuring chiral symmetry with non-equal sublattices include Lieb lattices, dice lattices, and particularly Moiré systems, where interaction converts the flat bands into fascinating many-body phases. In this work, we present a comprehensive classification theory for chiral symmetry with non-equal sublattices. First, we identify the classifying spaces as Stiefel manifolds and derive the topological classification table. Then, we extend the symmetry by taking $\mathcal{PT}$ symmetry into account, and ultimately obtain three symmetry classes corresponding to complex, real, and quaternionic Stiefel manifolds, respectively. Finally, we apply our theory to clarify the topological invariant for $\mathcal{PT}$-invariant Moiré systems and construct physical models with Lieb and dice lattice structures to demonstrate our theory. Our work establishes the theoretical foundation of topological phases protected by chiral symmetries with non-equal sublattices.
title Topological classification for chiral symmetry with non-equal sublattices
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2405.16001