Strain fingerprinting of exciton valley character in 2D semiconductors
Journal article, 2024
Intervalley excitons with electron and hole wavefunctions residing in different valleys determine the long-range transport and dynamics observed in many semiconductors. However, these excitons with vanishing oscillator strength do not directly couple to light and, hence, remain largely unstudied. Here, we develop a simple nanomechanical technique to control the energy hierarchy of valleys via their contrasting response to mechanical strain. We use our technique to discover previously inaccessible intervalley excitons associated with K, Γ, or Q valleys in prototypical 2D semiconductors WSe2 and WS2. We also demonstrate a new brightening mechanism, rendering an otherwise “dark” intervalley exciton visible via strain-controlled hybridization with an intravalley exciton. Moreover, we classify various localized excitons from their distinct strain response and achieve large tuning of their energy. Overall, our valley engineering approach establishes a new way to identify intervalley excitons and control their interactions in a diverse class of 2D systems.
Author
Abhijeet M. Kumar
Freie Universität Berlin
Denis Yagodkin
Freie Universität Berlin
Roberto Rosati
Philipps University Marburg
Douglas J. Bock
Freie Universität Berlin
Christoph Schattauer
Vienna University of Technology
Sarah Tobisch
Vienna University of Technology
Joakim Hagel
Chalmers, Physics, Condensed Matter and Materials Theory
Bianca Höfer
Freie Universität Berlin
Jan N. Kirchhof
Freie Universität Berlin
Kavli Institute of Nanoscience Delft
Pablo Hernández López
Humboldt University of Berlin
Kenneth Burfeindt
Freie Universität Berlin
Sebastian Heeg
Humboldt University of Berlin
Cornelius Gahl
Freie Universität Berlin
Florian Libisch
Vienna University of Technology
Ermin Malic
Philipps University Marburg
Kirill I. Bolotin
Freie Universität Berlin
Nature Communications
2041-1723 (ISSN) 20411723 (eISSN)
Vol. 15 1 7546Subject Categories (SSIF 2025)
Atom and Molecular Physics and Optics
Condensed Matter Physics
Other Physics Topics
DOI
10.1038/s41467-024-51195-y
Related datasets
Strain fingerpringting of exciton valley character in 2D semiconductors [dataset]
URI: https://zenodo.org/records/12699607