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TT: Fachverband Tiefe Temperaturen

TT 4: Graphene, 2D and Twisted Materials

TT 4.7: Vortrag

Montag, 9. März 2026, 11:15–11:30, HSZ/0105

Theory for optical control of correlated states in moiré transition metal dichalcogenide heterostructures — •Haoyang Tian and Urban F.P. Seifert — Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77a, 50937 Köln, Germany

In recent years, moiré transition metal dichalcogenide (TMD) heterostructures have emerged as highly versatile platforms for investigating phases and phenomena of strongly correlated electrons on emergent lattice scales. However, experimental characterization of the precise nature of some interaction-driven orders, in particular antiferromagnetism, and their excitations has remained a challenge. Given strong light-matter couplings and valley selection rules in TMD materials, ultrafast optical methods may constitute a promising avenue for probing and controlling these states and their collective modes.

In this work, we develop a theoretical framework to describe the coherent light-driven dynamics of type-II moiré TMD heterobilayers under circularly polarized laser irradiation. We construct a moiré-Floquet Hamiltonian for the electronic states under periodic driving. In the off-resonant regime, we find that the moiré valence band flattens due to hybridization with the photon-dressed conduction band and derive an effective low-energy model for the Floquet valence band. By incorporating electron-electron interactions via a Hartree-Fock framework, we analyze the impact of optical driving on the phase structure and collective excitations (e.g., magnons).

Keywords: Moiré transition metal dichalcogenides; Pump-probe spectroscopy; Magnetooptical effects