{
  "id": "2412.07993",
  "version": "v1",
  "published": "2024-12-11T00:08:09.000Z",
  "updated": "2024-12-11T00:08:09.000Z",
  "title": "Topological columnar nano-SQUID based on a 3D topological insulator",
  "authors": [
    "Ella Nikodem",
    "Jakob Schluck",
    "Henry F. Legg",
    "Max Geier",
    "Michal Papaj",
    "Mahasweta Bagchi",
    "Liang Fu",
    "Yoichi Ando"
  ],
  "comment": "22 pages total; 9 pages of main text with 4 figures, 13 pages of supplement with 11 figures. The raw data and codes are available at the online depository Zenodo with the identifier https://doi.org/10.5281/zenodo.14331680",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.mtrl-sci",
    "cond-mat.str-el",
    "cond-mat.supr-con"
  ],
  "abstract": "A 3D topological insulator (TI) is wrapped by a metallic surface that is topologically protected. While this surface is promising for generating non-Abelian Majorana zero-modes (MZMs) for topological quantum computing, it is a challenge to gap out the whole surface to get rid of low-energy quasiparticles to realize a well-defined fermion parity. Here we propose a novel TI platform that solves this problem and gives rise to a robust topological phase. It consists of a bulk-insulating rectangular TI nanowire laterally sandwiched by two superconductors. In this structure, the top and bottom surfaces individually work as SNS line junctions, forming a nanometer-scale columnar SQUID in which the nanowire cross-section defines the threading flux $\\Phi$. We demonstrate that a TI device of this structure indeed presents SQUID-type oscillations of the critical current $I_c$ as a function of the axial magnetic field with period $\\Phi_{0}^s=\\frac{h}{2e}$ and can be tuned by a back gate to attain vanishing $I_c$ minima, an indication that the supercurrent is completely surface-dominated. Our theory shows that, when the two junctions are asymmetric, a robust topological phase hosting MZMs occurs periodically for $(n-\\frac{1}{2})\\Phi_{0}^s < \\Phi < (n+\\frac{1}{2})\\Phi_{0}^s$ with odd-integer $n$.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-12-11T00:08:09.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "3d topological insulator",
      "topological columnar nano-squid",
      "phase hosting mzms occurs",
      "topological phase hosting mzms",
      "rectangular ti nanowire"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}