On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866913487383429120 |
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| author | Chen, Rui Shen, Shun-Qing |
| author_facet | Chen, Rui Shen, Shun-Qing |
| contents | In topological insulators, massive surface bands resulting from local symmetry breaking are believed to exhibit a half-quantized Hall conductance. However, such scenarios are obviously inconsistent with the Thouless-Kohmoto-Nightingale-Nijs theorem, which states that a single band in a lattice with a finite Brillouin zone can only have an integer-quantized Hall conductance. To explore this, we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator, Chern insulator, and semi-magnetic topological insulator phases. We reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance, respectively. This result is distinct from the previous consensus that the gapped surface band is responsible for the half-quantized Hall conductance and the gapless band should exhibit zero Hall response. We propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac fermions. The gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone, but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall conductance. The gapless state hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy, and thus the half-quantized Hall conductance can only originate from the gapless band. Moreover, we calculate the layer-resolved Hall conductance of the system. The conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2304_04229 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films Chen, Rui Shen, Shun-Qing Mesoscale and Nanoscale Physics In topological insulators, massive surface bands resulting from local symmetry breaking are believed to exhibit a half-quantized Hall conductance. However, such scenarios are obviously inconsistent with the Thouless-Kohmoto-Nightingale-Nijs theorem, which states that a single band in a lattice with a finite Brillouin zone can only have an integer-quantized Hall conductance. To explore this, we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator, Chern insulator, and semi-magnetic topological insulator phases. We reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance, respectively. This result is distinct from the previous consensus that the gapped surface band is responsible for the half-quantized Hall conductance and the gapless band should exhibit zero Hall response. We propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac fermions. The gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone, but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall conductance. The gapless state hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy, and thus the half-quantized Hall conductance can only originate from the gapless band. Moreover, we calculate the layer-resolved Hall conductance of the system. The conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model. |
| title | On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2304.04229 |