Twisted bilayer graphene in a parallel magnetic field

Yves H. Kwan, S. A. Parameswaran, S. L. Sondhi

Research output: Contribution to journalArticle

Abstract

We study the effect of an in-plane magnetic field on the noninteracting dispersion of twisted bilayer graphene. Our analysis is rooted in the chirally symmetric continuum model, whose zero-field band structure hosts exactly flat bands and large energy gaps at the magic angles. At the first magic angle, the central bands respond to a parallel field by forming a quadratic band crossing point (QBCP) at the moiré Brillouin zone center. Over a large range of fields, the dispersion is invariant with an overall scale set by the magnetic field strength. For deviations from the magic angle and for realistic interlayer couplings, the motion and merging of the Dirac points lying near charge neutrality are discussed in the context of the symmetries, and we show that small magnetic fields are able to induce a qualitative change in the energy spectrum. We conclude with a discussion on the possible ramifications of our study to the interacting ground states of twisted bilayer graphene systems.

Original languageEnglish (US)
Article number205116
JournalPhysical Review B
Volume101
Issue number20
DOIs
StatePublished - May 15 2020

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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