Floquet-engineering topological transitions in a twisted transition metal dichalcogenide homobilayer

Abstract

Motivated by the recent experimental realization of twisted transition metal dichalcogenide bilayers, we study a simplified model driven by different forms of monochromatic light. As a concrete and representative example we use parameters that correspond to a twisted MoTe${}_2$ homobilayer. First, we consider irradiation with circularly polarized light in free space and demonstrate that the corresponding Floquet Hamiltonian takes the same form as the static Hamiltonian, only with a constant overall shift in quasi-energy. This is in stark contrast to twisted bilayer graphene, where new terms are typically generated under an analagous drive. Longitudinal light, on the other hand, which can be generated from the transverse magnetic mode in a waveguide, has a much more dramatic effect--it renormalizes the tunneling strength between the layers, which effectively permits the tuning of the twist angle {\em in-situ}. We find that, by varying the frequency and amplitude of the drive, one can induce a topological transition that cannot be obtained with the traditional form of the Floquet drive in free space. Furthermore, we find that strong drives can have a profound effect on the layer pseudospin texture of the twisted system, which coincides with multiple simultaneous band gap closings in the infinite-frequency limit. Surprisingly, these bandgap closings are not associated with topological transitions. For high but finite drive frequencies near $0.7$eV, the infinite-frequency band crossings become band gap minima of the order of $10^{-6}$ eV or smaller.

References in corpus (21)

• Photovoltaic Hall effect in graphene
• The Magnus expansion and some of its applications
• Resonantly hybridised excitons in moiré superlattices in van der Waals heterostructures
• Periodically-driven quantum systems: Effective Hamiltonians and engineered gauge fields
• Irradiated graphene as a tunable Floquet topological insulator
• Configure polaritons in twisted $\alpha$-MoO3
• Tunable Spin-Orbit Coupling via Strong Driving in Ultracold Atom Systems
• All-optical band engineering of gapped Dirac materials
• Floquet band structure of a semi-Dirac system
• Effective Floquet Hamiltonian in the low-frequency regime
• Electronic localization in twisted bilayer MoS${}_2$ with small rotation angle
• Theory of tunable flux lattices in the homobilayer moiré of twisted and uniformly strained transition metal dichalcogenides
• Quadratic band touching points and flat bands in two-dimensional topological Floquet systems
• High-order nonlinear optical response of a twisted bilayer graphene
• Brillouin-Wigner Theory for Floquet Topological Phase Transitions in Spin-orbit Coupled Materials
• Periodic array of quantum rings strongly coupled to circularly polarized light as a topological insulator
• Floquet engineering of twisted double bilayer graphene
• Variational Schrieffer-Wolff Transformations for Quantum Many-Body Dynamics
• Perturbation theory for quasienergy (Floquet) solutions in the low-frequency regime of the oscillating electric field
• Moiré quantum well states in tiny angle two dimensional semi-conductors
• Artificial gauge fields and topological insulators in Moire superlattices

Cited by in corpus (4)

• Light-induced emergent phenomena in 2D materials and topological materials
• Signature of parity anomaly in the measurement of optical Hall conductivity in quantum anomalous Hall systems
• Low-frequency and Moiré Floquet engineering: a review
• Dynamical stabilization by vacuum fluctuations in a cavity: Resonant electron scattering in the ultrastrong light-matter coupling regime