Exciton broadening and band renormalization due to Dexter-like intervalley coupling
Journal article, 2018
A remarkable property of atomically thin transition metal dichalcogenides (TMDs) is the possibility to selectively address single valleys by circularly polarized light. In the context of technological applications, it is very important to understand possible intervalley coupling mechanisms. Here, we show how the Dexter-like intervalley coupling mixes A and B states from opposite valleys leading to a significant broadening gamma(B1s) of the B-1s exciton. The effect is much more pronounced in tungsten-based TMDs, where the coupling excitonic states are quasi-resonant. We calculate a ratio gamma(B1s)/gamma(A1s) approximate to 4.0, which is in good agreement with the experimentally measured value of 3.9 +/- 0.7. In addition to the broadening effect, the Dexter-like intervalley coupling also leads to a considerable energy renormalization resulting in an increased energetic distance between A(1s) and B-1s states.
linear optics
transition metal dichalcogenides
valleytronics
spintronics
Dexter interaction
excitonic physics
Author
Ivan Bernal
Chalmers, Physics, Condensed Matter Theory
Gunnar Berghäuser
Chalmers, Physics, Condensed Matter Theory
Malte Selig
Chalmers, Physics, Condensed Matter Theory
Tech Univ Berlin
Iris Niehues
Univ Munster
Robert Schmidt
Univ Munster
Robert Schneider
Univ Munster
Philipp Tonndorf
Univ Munster
Paul Erhart
Chalmers, Physics, Materials and Surface Theory
Steffen Michaelis de Vasconcellos
Univ Munster
Rudolf Bratschitsch
Univ Munster
Andreas Knorr
Tech Univ Berlin
Chalmers, Physics, Chemical Physics
Ermin Malic
Chalmers, Physics, Condensed Matter Theory
2D Materials
2053-1583 (eISSN)
Vol. 5 2 025011Subject Categories (SSIF 2011)
Atom and Molecular Physics and Optics
Theoretical Chemistry
Condensed Matter Physics
DOI
10.1088/2053-1583/aaaa8b