Transport and localization of indirect excitons in a van der Waals heterostructure

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Hauptverfasser: Fowler-Gerace, L. H., Zhou, Zhiwen, Szwed, E. A., Choksy, D. J., Butov, L. V.
Format: Preprint
Veröffentlicht: 2023
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author Fowler-Gerace, L. H.
Zhou, Zhiwen
Szwed, E. A.
Choksy, D. J.
Butov, L. V.
author_facet Fowler-Gerace, L. H.
Zhou, Zhiwen
Szwed, E. A.
Choksy, D. J.
Butov, L. V.
contents Long lifetimes of spatially indirect excitons (IXs), also known as interlayer excitons, allow implementing both quantum exciton systems and long-range exciton transport. Van der Waals heterostructures (HS) composed of atomically thin layers of transition-metal dichalcogenides (TMD) offer the opportunity to explore IXs in moiré superlattices. The moiré IXs in TMD HS form the materials platform for exploring the Bose-Hubbard physics and superfluid and insulating phases in periodic potentials. IX transport in TMD HS was intensively studied and diffusive IX transport with $1/e$ decay distances $d_{1/e}$ up to $\sim 3$ $μ$m was realized. In this work, we present in MoSe$_2$/WSe$_2$ HS the IX long-range transport with $d_{1/e}$ exceeding 100 $μ$m and diverging at the optical excitation resonant to spatially direct excitons. The IX long-range transport vanishes at high temperatures. With increasing IX density, IX localization, then IX long-range transport, and then IX reentrant localization is observed. The results are in qualitative agreement with the Bose-Hubbard theory of bosons in periodic potentials predicting superfluid at $N \sim 1/2$ and insulating at $N \sim 0$ and $N \sim 1$ phases for the number of bosons per site of the periodic potential $N$.
format Preprint
id arxiv_https___arxiv_org_abs_2307_00702
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Transport and localization of indirect excitons in a van der Waals heterostructure
Fowler-Gerace, L. H.
Zhou, Zhiwen
Szwed, E. A.
Choksy, D. J.
Butov, L. V.
Mesoscale and Nanoscale Physics
Long lifetimes of spatially indirect excitons (IXs), also known as interlayer excitons, allow implementing both quantum exciton systems and long-range exciton transport. Van der Waals heterostructures (HS) composed of atomically thin layers of transition-metal dichalcogenides (TMD) offer the opportunity to explore IXs in moiré superlattices. The moiré IXs in TMD HS form the materials platform for exploring the Bose-Hubbard physics and superfluid and insulating phases in periodic potentials. IX transport in TMD HS was intensively studied and diffusive IX transport with $1/e$ decay distances $d_{1/e}$ up to $\sim 3$ $μ$m was realized. In this work, we present in MoSe$_2$/WSe$_2$ HS the IX long-range transport with $d_{1/e}$ exceeding 100 $μ$m and diverging at the optical excitation resonant to spatially direct excitons. The IX long-range transport vanishes at high temperatures. With increasing IX density, IX localization, then IX long-range transport, and then IX reentrant localization is observed. The results are in qualitative agreement with the Bose-Hubbard theory of bosons in periodic potentials predicting superfluid at $N \sim 1/2$ and insulating at $N \sim 0$ and $N \sim 1$ phases for the number of bosons per site of the periodic potential $N$.
title Transport and localization of indirect excitons in a van der Waals heterostructure
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2307.00702