{
  "id": "2101.01790",
  "version": "v1",
  "published": "2021-01-05T21:26:39.000Z",
  "updated": "2021-01-05T21:26:39.000Z",
  "title": "Current Switching of Valley Polarization in Twisted Bilayer Graphene",
  "authors": [
    "Xuzhe Ying",
    "Mengxing Ye",
    "Leon Balents"
  ],
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.str-el"
  ],
  "abstract": "Twisted bilayer graphene (TBG) aligned with hexagonal boron nitride (h-BN) substrate can exhibit an anomalous Hall effect at 3/4 filling due to the spontaneous valley polarization in valley resolved moir\\'e bands with opposite Chern number [Science 367, 900 (2020), Science 365, 605 (2019)]. It was observed that a small DC current is able to switch the valley polarization and reverse the sign of the Hall conductance [Science 367, 900 (2020), Science 365, 605 (2019)]. Here, we discuss the mechanism of the current switching of valley polarization near the transition temperature, where bulk dissipative transport dominates. We show that for a sample with rotational symmetry breaking, a DC current may generate an electron density difference between the two valleys (valley density difference). The current induced valley density difference in turn induces a first order transition in the valley polarization. We emphasize that the inter-valley scattering plays a central role since it is the channel for exchanging electrons between the two valleys. We further estimate the valley density difference in the TBG/h-BN system with a microscopic model, and find a significant enhancement of the effect in the magic angle regime.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-01-05T21:26:39.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "valley polarization",
      "twisted bilayer graphene",
      "current switching",
      "current induced valley density difference",
      "small dc current"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}