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.


Koloman Wagner

University of Regensburg

Jonas Zipfel

University of Regensburg

Lawrence Berkeley National Laboratory

Roberto Rosati

Philipps University Marburg

Edith Wietek

University of Regensburg

Jonas D. Ziegler

University of Regensburg

Samuel Brem

Philipps University Marburg

Raul Perea Causin

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

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 076801

Graphene Core Project 3 (Graphene Flagship)

European Commission (EC) (881603GrapheneCore3), 2020-04-01 -- 2023-03-31.

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics



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