Misoriented bilayer graphene in a magnetic field: Optical transitions at commensurate angles

TL;DR

This paper investigates how the optical absorption spectra of misoriented bilayer graphene vary with twist angles in a magnetic field, revealing unique multi-peak structures at specific symmetric angles.

Contribution

It identifies special angles where bilayer graphene exhibits distinct optical features, linking symmetry to magneto-optical properties and suggesting a method to determine twist angles.

Findings

Single-peak spectra for general angles

Multi-peak structures at symmetric angles

Magneto-spectroscopy as a twist angle probe

Abstract

Misoriented bilayer graphene with commensurate angles shows unique magneto-optical properties. The optical absorption spectra of such a system strongly depend on the angle of rotation. For a general commensurate twist angle the absorption spectra has a simple single-peak structure. However, our studies indicate that there are special angles at which the absorption spectra of the rotated bilayer exhibit well developed multi-peak structures. These angles correspond to even symmetry of the rotated graphene with respect to the sublattice exchange. Magneto-spectroscopy can therefore be a potentially useful scheme to determine the twist angles.