Ultrafast Nanoscopy of High-Density Exciton Phases in WSe2
Artikel i vetenskaplig tidskrift, 2022

The density-driven transition of an exciton gas into an electron-hole plasma remains a compelling question in condensed matter physics. In two-dimensional transition metal dichalcogenides, strongly bound excitons can undergo this phase change after transient injection of electron-hole pairs. Unfortunately, unavoidable nanoscale inhomogeneity in these materials has impeded quantitative investigation into this elusive transition. Here, we demonstrate how ultrafast polarization nanoscopy can capture the Mott transition through the density-dependent recombination dynamics of electron-hole pairs within a WSe2 homobilayer. For increasing carrier density, an initial monomolecular recombination of optically dark excitons transitions continuously into a bimolecular recombination of an unbound electron-hole plasma above 7 × 1012 cm-2. We resolve how the Mott transition modulates over nanometer length scales, directly evidencing the strong inhomogeneity in stacked monolayers. Our results demonstrate how ultrafast polarization nanoscopy could unveil the interplay of strong electronic correlations and interlayer coupling within a diverse range of stacked and twisted two-dimensional materials.

transition metal dichalcogenides

Mott transition

near-field microscopy

ultrafast dynamics




Thomas Siday

Universität Regensburg

Fabian Sandner

Universität Regensburg

Samuel Brem

Chalmers, Fysik, Kondenserad materie- och materialteori

Philipps-Universität Marburg

Martin Zizlsperger

Universität Regensburg

Raul Perea Causin

Chalmers, Fysik, Kondenserad materie- och materialteori

Felix Schiegl

Universität Regensburg

Svenja Nerreter

Universität Regensburg

Markus Plankl

Universität Regensburg

Philipp Merkl

Universität Regensburg

F. Mooshammer

Columbia University

Universität Regensburg

Markus A. Huber

Universität Regensburg

Ermin Malic

Philipps-Universität Marburg

Chalmers, Fysik, Kondenserad materie- och materialteori

R. Huber

Universität Regensburg

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. In Press

Graphene Core Project 3 (Graphene Flagship)

Europeiska kommissionen (EU) (EC/H2020/881603), 2020-04-01 -- 2023-03-31.


Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik





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