$${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect

Abstract The half-quantized Hall phase represents a unique metallic or semi-metallic state of matter characterized by a fractional quantum Hall conductance, precisely half of an integer ν multiple of e 2/h. Here we demonstrate the existence of a $${\mathbb{Z}}/2$$ Z / 2 topological invariant that se...

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Main Authors: Bo Fu, Shun-Qing Shen
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:Communications Physics
Online Access:https://doi.org/10.1038/s42005-024-01926-w
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author Bo Fu
Shun-Qing Shen
author_facet Bo Fu
Shun-Qing Shen
author_sort Bo Fu
collection DOAJ
description Abstract The half-quantized Hall phase represents a unique metallic or semi-metallic state of matter characterized by a fractional quantum Hall conductance, precisely half of an integer ν multiple of e 2/h. Here we demonstrate the existence of a $${\mathbb{Z}}/2$$ Z / 2 topological invariant that sets the half-quantized Hall phase apart from two-dimensional ordinary metallic ferromagnets. The $${\mathbb{Z}}/2$$ Z / 2 classification is determined by the line integral of the intrinsic anomalous Hall conductance, which is safeguarded by two distinct categories of local unitary and anti-unitary symmetries in proximity to the Fermi surface of electron states. We further validate the $${\mathbb{Z}}/2$$ Z / 2 topological order in the context of the quantized Hall phase by examining semi-magnetic topological insulator Bi2Te3 and Bi2Se3 film for ν = 1 and topological crystalline insulator SnTe films for ν = 2 or 4. Our findings pave the way for future exploration and understanding of topological metals and their unique properties.
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spelling doaj-art-e0b7de0059764c8fb3e953d5fd6fd7c92025-01-05T12:32:41ZengNature PortfolioCommunications Physics2399-36502025-01-018111410.1038/s42005-024-01926-w$${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effectBo Fu0Shun-Qing Shen1School of Sciences, Great Bay UniversityDepartment of Physics, The University of Hong KongAbstract The half-quantized Hall phase represents a unique metallic or semi-metallic state of matter characterized by a fractional quantum Hall conductance, precisely half of an integer ν multiple of e 2/h. Here we demonstrate the existence of a $${\mathbb{Z}}/2$$ Z / 2 topological invariant that sets the half-quantized Hall phase apart from two-dimensional ordinary metallic ferromagnets. The $${\mathbb{Z}}/2$$ Z / 2 classification is determined by the line integral of the intrinsic anomalous Hall conductance, which is safeguarded by two distinct categories of local unitary and anti-unitary symmetries in proximity to the Fermi surface of electron states. We further validate the $${\mathbb{Z}}/2$$ Z / 2 topological order in the context of the quantized Hall phase by examining semi-magnetic topological insulator Bi2Te3 and Bi2Se3 film for ν = 1 and topological crystalline insulator SnTe films for ν = 2 or 4. Our findings pave the way for future exploration and understanding of topological metals and their unique properties.https://doi.org/10.1038/s42005-024-01926-w
spellingShingle Bo Fu
Shun-Qing Shen
$${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
Communications Physics
title $${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
title_full $${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
title_fullStr $${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
title_full_unstemmed $${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
title_short $${\mathbb{Z}}/2$$ Z / 2 topological invariants and the half quantized Hall effect
title_sort mathbb z 2 z 2 topological invariants and the half quantized hall effect
url https://doi.org/10.1038/s42005-024-01926-w
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