Topological Floquet Engineering of Twisted Bilayer Graphene

In twisted bilayer graphene (TBG), the choice of the twist angle allows for tailored engineering of the low energy absorption spectrum. This tunability makes TBG a perfect playground for Floquet engineering. Motivated by the measurement of ultrafast light-induced Hall currents in monolayer graphene [1], we investigate the topological properties of twisted bilayer graphene for an intermediate twisting angle in and out of equilibrium on the basis a full Moiré-unit-cell tight-binding model [2]. By breaking time-reversal symmetry with a circularly polarized light field, we induce a transition to a topologically non-trivial Floquet band structure with a Berry curvature analogous to a Chern insulator, which can be controlled via inversion-symmetry-breaking back-gate potentials. Additionally, I will discuss preliminary results of my ongoing work on light-matter couplings in magic-angle twisted bilayer graphene (MATBG).

[1] J. M. McIver et al., Nature Physics 16, 38-41 (2020)
[2] G. E. Topp et al. PRR 1, 023031 (2019)