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O: Fachverband Oberflächenphysik
O 9: Ultrafast Electron Dynamics at Surfaces and Interfaces 2
O 9.8: Vortrag
Montag, 5. September 2022, 16:45–17:00, H3
k-dependent band gap renormalization in monolayer WS2 revealed by tr-ARPES — •Niklas Hofmann1, Alexander Steinhoff2, Leonard Weigl1, Johannes Gradl1, Tim Wehling2,3, Sivan Refaely-Abramson4, Neeraj Mishra5,6, Stiven Forti5, Camilla Coletti5,6, and Isabella Gierz1 — 1University of Regensburg, 93040 Regensburg, Germany — 2University of Bremen, 28359 Bremen, Germany — 3University of Hamburg, 22607 Hamburg, Germany — 4Weizmann Institute of Science, 7610001 Rehovot, Israel — 5Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, 56127 Pisa, Italy — 6Graphene Labs, Istituto Italiano di Tecnologia, 16163 Genova, Italy
Monolayer transition-metal dichalcogenides show strong enhancement of Coulomb interactions due to their reduced dimensionality with immediate effects on both the optical as well as the single-particle band gap. Photogenerated electron-hole pairs have been shown to result in a giant band gap renormalization that has been attributed to efficient screening of the Coulomb interaction. The corresponding band structure changes are predicted to show a pronounced momentum dependence that we resolve using time- and angle-resolved photoemission spectroscopy on monolayer WS2 supported by a graphene substrate. Excellent agreement with ab initio calculations allows us to disentangle the intricate interplay of different many-body contributions to the observed transient band structure renormalization with important implications for the optoelectronic properties of 2D semiconductors.