{
  "id": "1910.07863",
  "version": "v1",
  "published": "2019-10-17T12:45:59.000Z",
  "updated": "2019-10-17T12:45:59.000Z",
  "title": "Quantum confinement of the Dirac surface states in topological-insulator nanowires",
  "authors": [
    "Felix Münning",
    "Oliver Breunig",
    "Henry F. Legg",
    "Stefan Roitsch",
    "Dingxun Fan",
    "Matthias Rößler",
    "Achim Rosch",
    "Yoichi Ando"
  ],
  "comment": "7 pages main text, 6 pages supplemental material",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.mtrl-sci",
    "cond-mat.str-el"
  ],
  "abstract": "The non-trivial topology of the three-dimensional (3D) topological insulator (TI) dictates the appearance of gapless Dirac surface states. Intriguingly, when a 3D TI is made into a nanowire, a gap opens at the Dirac point due to the quantum confinement, leading to a peculiar Dirac sub-band structure. This gap is useful for, e.g., future Majorana qubits based on TIs. Furthermore, these Dirac sub-bands can be manipulated by a magnetic flux and are an ideal platform for generating stable Majorana zero modes (MZMs), which play a key role in topological quantum computing. However, direct evidence for the Dirac sub-bands in TI nanowires has not been reported so far. Here we show that by growing very thin ($\\sim$40-nm diameter) nanowires of the bulk-insulating topological insulator (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ and by tuning its chemical potential across the Dirac point with gating, one can unambiguously identify the Dirac sub-band structure. Specifically, the resistance measured on gate-tunable four-terminal devices was found to present non-equidistant peaks as a function of the gate voltage, which we theoretically show to be the unique signature of the quantum-confined Dirac surface states. These TI nanowires open the way to address the topological mesoscopic physics, and eventually the Majorana physics when proximitised by an $s$-wave superconductor.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-10-17T12:45:59.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "dirac surface states",
      "quantum confinement",
      "topological-insulator nanowires",
      "stable majorana zero modes",
      "ti nanowires"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}