Exciton-Driven Renormalization of Quasiparticle Band Structure in Monolayer MoS2

Abstract

Optical excitation serves as a powerful approach to control the electronic structure of layered Van der Waals materials via many-body screening effects, induced by photoexcited free carriers, or via light-driven coherence, such as optical Stark and Bloch-Siegert effects. Although theoretical work has also pointed to an exotic mechanism of renormalizing band structure via excitonic correlations in bound electron-hole pairs (excitons), experimental observation of such exciton-driven band renormalization and the full extent of their implications is still lacking, largely due to the limitations of optical probes and the impact of screening effects. Here, by using extreme-ultraviolet time-resolved angle-resolved photoemission spectroscopy together with excitonic many-body theoretical calculations, we directly unmask the band renormalization effects driven by excitonic correlations in a monolayer semiconductor. We revealed a surprising bandgap opening, increased by 40 meV, and a simultaneous enhancement of band effective mass. Our findings unmask the novel exciton-driven mechanism towards the band engineering in photoexcited semiconducting materials, opening a new playground to manipulate the transient energy states in layered quantum materials via optical controls of excitonic many-body correlations.

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Cited by in corpus (11)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• Ultrafast dynamics of bright and dark excitons in monolayer WSe${}_2$ and heterobilayer WSe${}_2$/MoS${}_2$
• Advancing time- and angle-resolved photoemission spectroscopy: The role of ultrafast laser development
• Ultrafast creation of a light induced semimetallic state in strongly excited 1T-TiSe${}_2$
• Probing excitons with time-resolved momentum microscopy
• Excitonic Bloch equations from first principles
• Retrieval of material properties of monolayer transition-metal dichalcogenides from magnetoexciton energy spectra
• k-resolved ultrafast light-induced band renormalization in monolayer WS${}_2$ on graphene
• Dynamic screening of quasiparticles in WS${}_2$ monolayers
• Light-matter interactions in layered materials and heterostructures: from moiré physics and magneto-optical effects to ultrafast dynamics and hybrid meta-photonics
• Retrieval of fundamental material parameters of monolayer transition metal dichalcogenides from experimental exciton energies: An analytical approach