Pressure-induced metal-insulator transition in twisted bilayer graphene

Bikash Padhi, Philip W. Phillips

Research output: Contribution to journalArticlepeer-review

Abstract

Recent experiments on twisted bilayer graphene (TBLG) have observed insulating states for two and three unit charges per moiré supercell, whereas the quarter-filling state (QFS) remained metallic. Subsequent experiments show that under hydrostatic pressure the QFS turns insulating for a certain window of pressure. In fact, the resistivity of the 1/2-filling and 3/4-filling states are also enhanced in the same pressure-window. Using pressure-dependent band structure calculations we compute the ratio of the potential to the kinetic energy, rs. We find a window of pressure for which rs crosses the threshold for a triangular Wigner crystal, thereby corroborating our previous work that the insulating states in TBLG are driven by Wigner physics, A key prediction of this work is that the window for the onset of the hierarchy of Wigner states that obtains at commensurate fillings conforms to a dome shape under pressure. We also predict the optimal condition for Wigner crystallization to be around 1.5GPa. Consequently, TBLG provides a new platform for the exploration of Wigner physics and its relationship with superconductivity.

Original languageEnglish (US)
Article number205141
JournalPhysical Review B
Volume99
Issue number20
DOIs
StatePublished - May 24 2019

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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