Nodal Surfaces in Photoemission from Twisted Bilayer Graphene

TL;DR

This paper investigates how angle-resolved photoemission spectra reveal the electronic structure, interference effects, and interlayer coherence in twisted bilayer graphene using a long wavelength theoretical approach.

Contribution

It introduces a generic model for interlayer coupling and identifies spectral features controlled by singularities, gauge potentials, and interference effects in twisted bilayer graphene.

Findings

Spectral features are influenced by singularities and topological properties.

Interlayer coherence can be probed through energy- and polarization-dependent ARPES spectra.

The model helps characterize interlayer coupling in twisted bilayer graphene.

Abstract

Selection rules and interference effects in angle resolved photoemission spectra from twisted graphene bilayers are studied within a long wavelength theory for the electronic structure. Using a generic model for the interlayer coupling, we identify features in the calculated ARPES momentum distributions that are controlled by the singularities and topological character of its long wavelength spectrum. We distinguish spectral features that are controlled by single-layer singularities in the spectrum, their modification by gauge potentials in each layer generated by the interlayer coupling, and new energy-dependent interference effects that directly probe the interlayer coherence. The results demonstrate how the energy- and polarization- dependence of ARPES spectra can be used to characterize the interlayer coupling in twisted bilayer graphenes.