Giant self-driven exciton-Floquet signatures in time-resolved photoemission spectroscopy of MoS$_2$ from time-dependent GW approach

TL;DR

This paper introduces an ab initio time-domain GW approach to TR-ARPES, revealing giant exciton-Floquet signatures in monolayer MoS$_2$ that enable direct measurement and understanding of excitonic effects under optical excitation.

Contribution

The paper develops a novel time-dependent GW method for TR-ARPES and demonstrates its ability to detect strong exciton-Floquet phenomena in monolayer MoS$_2$.

Findings

Excitons appear as satellite bands in TR-ARPES spectra.

Exciton-induced band renormalization is observed.

Giant exciton-Floquet effects are significantly stronger than laser-induced Floquet bands.

Abstract

Time-resolved, angle-resolved photoemission spectroscopy (TR-ARPES) is a one-particle spectroscopic technique that can probe excitons (two-particle excitations) in momentum space. We present an ab initio, time-domain GW approach to TR-ARPES and apply it to monolayer MoS$_2$. We show that photoexcited excitons may be measured and quantified as satellite bands, as well as leading to the renormalization of the quasiparticle bands. These features are explained in terms of an exciton- Floquet phenomenon induced by an exciton time-dependent bosonic field, which is orders of magnitude stronger than laser field induced Floquet bands in low-dimensional semiconductors. Our findings open a door to understanding the behavior of optical-field driven materials.