{
  "id": "2304.04229",
  "version": "v1",
  "published": "2023-04-09T12:48:44.000Z",
  "updated": "2023-04-09T12:48:44.000Z",
  "title": "On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films",
  "authors": [
    "Rui Chen",
    "Shun-Qing Shen"
  ],
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "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.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-04-09T12:48:44.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "half-quantized hall conductance",
      "magnetic topological insulator film",
      "massive surface electrons",
      "integer-quantized hall conductance",
      "gapped surface band"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}