Nonclassical Exciton Diffusion in Monolayer WSe2
Journal article, 2021
We experimentally demonstrate time-resolved exciton propagation in a monolayer semiconductor at cryogenic temperatures. Monitoring phonon-assisted recombination of dark states, we find a highly unusual case of exciton diffusion. While at 5 K the diffusivity is intrinsically limited by acoustic phonon scattering, we observe a pronounced decrease of the diffusion coefficient with increasing temperature, far below the activation threshold of higher-energy phonon modes. This behavior corresponds neither to well-known regimes of semiclassical free-particle transport nor to the thermally activated hopping in systems with strong localization. Its origin is discussed in the framework of both microscopic numerical and semiphenomenological analytical models illustrating the observed characteristics of nonclassical propagation. Challenging the established description of mobile excitons in monolayer semiconductors, these results open up avenues to study quantum transport phenomena for excitonic quasiparticles in atomically thin van der Waals materials and their heterostructures.
Author
Koloman Wagner
University of Regensburg
Jonas Zipfel
Lawrence Berkeley National Laboratory
University of Regensburg
Roberto Rosati
Philipps University Marburg
Edith Wietek
University of Regensburg
Jonas D. Ziegler
University of Regensburg
Samuel Brem
Philipps University Marburg
Raul Perea Causin
2D-Tech
Chalmers, Physics, Condensed Matter and Materials Theory
Takashi Taniguchi
National Institute for Materials Science (NIMS)
Kenji Watanabe
National Institute for Materials Science (NIMS)
Mikhail M. Glazov
Russian Academy of Sciences
Ermin Malic
2D-Tech
Chalmers, Physics, Condensed Matter and Materials Theory
Alexey Chernikov
University of Regensburg
Technische Universität Dresden
Physical Review Letters
0031-9007 (ISSN) 1079-7114 (eISSN)
Vol. 127 7 0768012D material-based technology for industrial applications (2D-TECH)
VINNOVA (2019-00068), 2020-05-01 -- 2024-12-31.
GKN Aerospace Sweden (2D-tech), 2021-01-01 -- 2024-12-31.
Graphene Core Project 3 (Graphene Flagship)
European Commission (EC) (EC/H2020/881603), 2020-04-01 -- 2023-03-31.
Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1103/PhysRevLett.127.076801