Giant self-driven exciton-Floquet signatures in time-resolved photoemission spectroscopy of MoS<sub>2</sub> from time-dependent GW approach.

Chan, Y-H; Qiu, Diana Y; da Jornada, Felipe H; Louie, Steven G · Proc Natl Acad Sci U S A · 2023

basic_science · Level V

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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<sub>2</sub>. We show that photoexcited excitons may be measured and quantified as satellite bands and lead 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 are orders of magnitude stronger than those of laser field-induced Floquet bands in low-dimensional semiconductors. Our findings imply a way to engineer Floquet matter through the coherent oscillation of excitons and open the new door for mechanisms for band structure engineering.