Optical absorption in twisted bilayer graphene

Pilkyung Moon, Mikito Koshino

Research output: Contribution to journalArticlepeer-review

154 Citations (Scopus)

Abstract

We theoretically study the optical absorption property of twisted bilayer graphenes with various stacking geometries and demonstrate that the spectroscopic characteristics serve as a fingerprint to identify the rotation angle between two layers. We find that the absorption spectrum almost continuously evolves in changing the rotation angle, regardless of the lattice commensurability. The spectrum is characterized by series of peaks associated with the van Hove singularity, and the peak energies systematically shift with the rotation angle. We calculate the optical absorption in two frameworks: the tight-binding model and the effective continuum model based on the Dirac equation. For small rotation angles, less than 10 the effective model well reproduces the low-energy band structure and the optical conductivity of the tight-binding model and, also, explains the optical selection rule analytically in terms of the symmetry of the effective Hamiltonian.

Original languageEnglish
Article number205404
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number20
DOIs
Publication statusPublished - 2013 May 2

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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