{
  "id": "2202.05663",
  "version": "v1",
  "published": "2022-02-11T15:01:57.000Z",
  "updated": "2022-02-11T15:01:57.000Z",
  "title": "Valley-Polarized State Induced $\\varphi_0$-Josephson Junction in Twisted Bilayer Graphene",
  "authors": [
    "Ying-Ming Xie",
    "Dmitri K. Efetov",
    "K. T. Law"
  ],
  "comment": "7 pages, 4 figures, plus Supplementary Material",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.mtrl-sci",
    "cond-mat.str-el",
    "cond-mat.supr-con"
  ],
  "abstract": "Recently, gate-defined Josephson junctions in magic angle twisted bilayer graphene (MATBG) were studied experimentally and highly unconventional Fraunhofer patterns were observed. In this work, we show that an interaction-driven valley-polarized state connecting two superconducting regions of MATBG would give rise to a long-sought-after purely electric controlled $\\varphi_0$-junction in which the two superconductors acquire a finite phase difference $\\varphi_0$ in the ground state. We point out that the emergence of the $\\varphi_0$-junction stems from the time-reversal symmetry breaking valley polarization and an intravalley inversion symmetry breaking term. Importantly, a spatially non-uniform valley polarization order parameter at the junction can explain the highly unconventional Fraunhofer patterns observed in the experiment. Our work explores the novel transport properties of the valley-polarized state and suggests that gate-defined MATBG Josephson junctions could realize the first purely electric controlled $\\varphi_0$-junctions with applications in superconducting devices.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-02-11T15:01:57.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "josephson junction",
      "valley-polarized state",
      "non-uniform valley polarization order",
      "valley polarization order parameter",
      "symmetry breaking valley polarization"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}