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
exciton
terahertz
Författare
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. 22 6 2561-2568Graphene Core Project 3 (Graphene Flagship)
Europeiska kommissionen (EU) (EC/H2020/881603), 2020-04-01 -- 2023-03-31.
Ämneskategorier
Atom- och molekylfysik och optik
Annan fysik
Den kondenserade materiens fysik
DOI
10.1021/acs.nanolett.1c04741
PubMed
35157466