Magic-angle twisted bilayer graphene under orthogonal and in-plane magnetic fields

TL;DR

This paper studies how orthogonal and in-plane magnetic fields influence the electronic band structure of magic-angle twisted bilayer graphene, revealing dispersive Landau levels and band modifications due to magnetic coupling.

Contribution

It introduces a combined tight-binding and Peierls phase approach to analyze magnetic effects on twisted bilayer graphene's band structure.

Findings

Landau levels become dispersive under orthogonal magnetic fields

High in-plane magnetic fields alter low-energy bands and gaps

Magnetic coupling directly affects the band structure modifications

Abstract

We investigate the effect of a magnetic field on the band structure of bilayer graphene with a magic twist angle of 1.08{\deg}. The coupling of a tight-binding model and the Peierls phase allows the calculation of the energy bands of periodic two-dimensional systems. For an orthogonal magnetic field, the Landau levels are dispersive, particularly for magnetic lengths comparable to or larger than the twisted bilayer cell size. A high in-plane magnetic field modifies the low-energy bands and gap, which we demonstrate to be a direct consequence of the minimal coupling.