Tuning the magic angle of twisted bilayer graphene at the exit of a waveguide

Michael Vogl, Martin Rodriguez-Vega, Gregory A. Fiete

Published 2020-01-13Version 1

In this paper, we introduce a new method that allows reducing the strength of the interlayer couplings in few-layer van der Waals heterostructures by irradiating them with longitudinal waves of light. As a specific application, we consider twisted bilayer graphene and show that we can tune the magic angles in a controlled manner. Maxwell's equations tell us that the electromagnetic fields associated with light in a vacuum do not possess longitudinal components. However, this can be circumvented using waveguides, where longitudinal components can be generated. Boundary conditions imposed by a metallic surface make it possible to generate transverse magnetic modes (TM). We propose to place twisted bilayer graphene at a specific location at the exit of a waveguide, such that it is subjected to purely longitudinal components of a TM wave. We derive an analytic model to predict the magic angle as a function of the drive and waveguide parameters. This approach could be employed in experiments to tune the Fermi velocity in experiments and explore the strongly correlated physics in-situ.