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Jash A, Stern M, Misra S, Umansky V, Joseph IB. Giant hyperfine interaction between a dark exciton condensate and nuclei. SCIENCE ADVANCES 2024; 10:eado8763. [PMID: 39151004 PMCID: PMC11328897 DOI: 10.1126/sciadv.ado8763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/11/2024] [Indexed: 08/18/2024]
Abstract
We study the interaction of a dark exciton Bose-Einstein condensate with the nuclei in gallium arsenide/aluminum gallium arsenide coupled quantum wells and find clear evidence for nuclear polarization buildup that accompanies the appearance of the condensate. We show that the nuclei are polarized throughout the mesa area, extending to regions that are far away from the photoexcitation area and persisting for seconds after the excitation is switched off. Photoluminescence measurements in the presence of radio frequency radiation reveal that the hyperfine interaction between the nuclear and electron spins is enhanced by two orders of magnitude. We suggest that this large enhancement manifests the collective nature of the N-exciton condensate, which amplifies the interaction by a factor of [Formula: see text].
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Affiliation(s)
- Amit Jash
- Department of Condensed Matter physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michael Stern
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Subhradeep Misra
- Department of Condensed Matter physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Vladimir Umansky
- Department of Condensed Matter physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Israel Bar Joseph
- Department of Condensed Matter physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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2
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Wrona PR, Rabani E, Geissler PL. A Pair of 2D Quantum Liquids: Investigating the Phase Behavior of Indirect Excitons. ACS NANO 2022; 16:15339-15346. [PMID: 36069715 PMCID: PMC9527805 DOI: 10.1021/acsnano.2c06947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
Long-lived indirect excitons (IXs) exhibit a rich phase diagram, including a Bose-Einstein condensate (BEC), a Wigner crystal, and other exotic phases. Recent experiments have hinted at a "classical" liquid of IXs above the BEC transition. To uncover the nature of this phase, we use a broad range of theoretical tools and find no evidence of a driving force toward classical condensation. Instead, we attribute the condensed phase to a quantum electron-hole liquid (EHL), first proposed by Keldysh for direct excitons. Taking into account the association of free carriers into bound excitons, we study the phase equilibrium between a gas of excitons, a gas of free carriers, and an EHL for a wide range of electron-hole separations, temperatures, densities, and mass ratios. Our results agree reasonably well with recent measurements of GaAs/AlGaAs coupled quantum wells.
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Affiliation(s)
- Paul R. Wrona
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Eran Rabani
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- The
Raymond and Beverly Sackler Center of Computational Molecular and
Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
| | - Phillip L. Geissler
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
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3
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Abstract
We show that a Bose-Einstein condensate consisting of dark excitons forms in GaAs coupled quantum wells at low temperatures. We find that the condensate extends over hundreds of micrometers, well beyond the optical excitation region, and is limited only by the boundaries of the mesa. We show that the condensate density is determined by spin-flipping collisions among the excitons, which convert dark excitons into bright ones. The suppression of this process at low temperature yields a density buildup, manifested as a temperature-dependent blueshift of the exciton emission line. Measurements under an in-plane magnetic field allow us to preferentially modify the bright exciton density and determine their role in the system dynamics. We find that their interaction with the condensate leads to its depletion. We present a simple rate-equations model, which well reproduces the observed temperature, power, and magnetic-field dependence of the exciton density.
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Zimmerman M, Rapaport R, Gazit S. Collective interlayer pairing and pair superfluidity in vertically stacked layers of dipolar excitons. Proc Natl Acad Sci U S A 2022; 119:e2205845119. [PMID: 35858431 PMCID: PMC9335227 DOI: 10.1073/pnas.2205845119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/06/2022] [Indexed: 01/21/2023] Open
Abstract
Layered bosonic dipolar fluids have been suggested to host a condensate of interlayer molecular bound states. However, experimental observation has remained elusive. Motivated by two recent experimental works [C. Hubert et al., Phys. Rev. X9, 021026 (2019) and D. J. Choksy et al., Phys. Rev. B 103, 045126 (2021)], we theoretically study, using numerically exact quantum Monte Carlo calculations, the experimental signatures of collective interlayer pairing in vertically stacked indirect exciton (IX) layers. We find that IX energy shifts associated with each layer evolve nontrivially as a function of density imbalance following a nonmonotonic trend with a jump discontinuity at density balance, identified with the interlayer IX molecule gap. This behavior discriminates between the superfluidity of interlayer bound pairs and independent dipole condensation in distinct layers. Considering finite temperature and finite density imbalance conditions, we find a cascade of Berezinskii-Kosterlitz-Thouless (BKT) transitions, initially into a pair superfluid and only then, at lower temperatures, into complete superfluidity of both layers. Our results may provide a theoretical interpretation of existing experimental observations in GaAs double quantum well (DQW) bilayer structures. Furthermore, to optimize the visibility of pairing dynamics in future studies, we present an analysis suggesting realistic experimental settings in GaAs and transition metal dichalcogenide (TMD) bilayer DQW heterostructures where collective interlayer pairing and pair superfluidity can be clearly observed.
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Affiliation(s)
- Michal Zimmerman
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ronen Rapaport
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Snir Gazit
- The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
- The Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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Qi P, Luo Y, Li W, Cheng Y, Shan H, Wang X, Liu Z, Ajayan PM, Lou J, Hou Y, Liu K, Fang Z. Remote Lightening and Ultrafast Transition: Intrinsic Modulation of Exciton Spatiotemporal Dynamics in Monolayer MoS 2. ACS NANO 2020; 14:6897-6905. [PMID: 32491833 DOI: 10.1021/acsnano.0c01165] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Devices operating with excitons have promising prospects for overcoming the dilemma of response time and integration in current generation of electron- or/and photon-based elements and devices. Although the intrinsic properties including edges, grain boundaries, and defects of atomically thin semiconductors have been demonstrated as a powerful tool to adjust the bandgap and exciton energy, investigating the intrinsic modulation of spatiotemporal dynamics still remains challenging on account of the short exciton diffusion length. Here, we achieve the attractive remote lightening phenomenon, in which the emission region could be far away (up to 14.6 μm) from the excitation center, by utilizing a femtosecond laser with ultrahigh peak power as excitation source and the edge region with high photoluminescence efficiency as a bright emitter. Furthermore, the ultrafast transition between exciton and trion is demonstrated, which provides insight into the intrinsic modulation on populations of exciton and trion states. The complete cascaded physical scenario of exciton spatiotemporal dynamics is eventually established. This work can refresh our perspective on the spatial nonuniformities of CVD-grown atomically thin semiconductors and provide important implications for developing durable and stable excitonic devices in the future.
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Affiliation(s)
- Pengfei Qi
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
| | - Yang Luo
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
| | - Wei Li
- Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Centre for Engineering Science and Advanced Technology, Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Yang Cheng
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
| | - Hangyong Shan
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
| | - Xingli Wang
- CNRS International-NTU-Thales Research Alliance (CINTRA), Nanyang Technological University, Singapore 637553, Singapore
| | - Zheng Liu
- CNRS International-NTU-Thales Research Alliance (CINTRA), Nanyang Technological University, Singapore 637553, Singapore
| | - Pulickel M Ajayan
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Jun Lou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Yanglong Hou
- Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing Innovation Centre for Engineering Science and Advanced Technology, Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Kaihui Liu
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
| | - Zheyu Fang
- School of Physics, State Key Laboratory for Mesoscopic Physics, Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Nano-optoelectronics Frontier Center of Ministry of Education, Peking University, Beijing 100871, China
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Dynamical formation of a strongly correlated dark condensate of dipolar excitons. Proc Natl Acad Sci U S A 2019; 116:18328-18333. [PMID: 31451654 DOI: 10.1073/pnas.1903374116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Strongly interacting bosons display a rich variety of quantum phases, the study of which has so far been focused in the dilute regime, at a fixed number of particles. Here we demonstrate the formation of a dense Bose-Einstein condensate in a long-lived dark spin state of 2D dipolar excitons. A dark condensate of weakly interacting excitons is very fragile, being unstable against a coherent coupling of dark and bright spin states. Remarkably, we find that strong dipole-dipole interactions stabilize the dark condensate. As a result, the dark phase persists up to densities high enough for a dark quantum liquid to form. The striking experimental observation of a step-like dependence of the exciton density on the pump power is reproduced quantitatively by a model describing the nonequilibrium dynamics of driven coupled dark and bright condensates. This unique behavior marks a dynamical condensation to dark states with lifetimes as long as a millisecond, followed by a brightening transition at high densities.
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Chiaruttini F, Guillet T, Brimont C, Jouault B, Lefebvre P, Vives J, Chenot S, Cordier Y, Damilano B, Vladimirova M. Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures. NANO LETTERS 2019; 19:4911-4918. [PMID: 31241962 DOI: 10.1021/acs.nanolett.9b00914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Dipolar excitons offer a rich playground for both design of novel optoelectronic devices and fundamental many-body physics. Wide GaN/(AlGa)N quantum wells host a new and promising realization of dipolar excitons. We demonstrate the in-plane confinement and cooling of these excitons, when trapped in the electrostatic potential created by semitransparent electrodes of various shapes deposited on the sample surface. This result is a prerequisite for the electrical control of the exciton densities and fluxes, as well for studies of the complex phase diagram of these dipolar bosons at low temperature.
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Affiliation(s)
- François Chiaruttini
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
| | - Thierry Guillet
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
| | - Christelle Brimont
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
| | - Benoit Jouault
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
| | - Pierre Lefebvre
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
| | - Jessica Vives
- CRHEA , Université Côte d'Azur, CNRS, Rue Bernard Gregory , F-06560 , Valbonne , France
| | - Sebastien Chenot
- CRHEA , Université Côte d'Azur, CNRS, Rue Bernard Gregory , F-06560 , Valbonne , France
| | - Yvon Cordier
- CRHEA , Université Côte d'Azur, CNRS, Rue Bernard Gregory , F-06560 , Valbonne , France
| | - Benjamin Damilano
- CRHEA , Université Côte d'Azur, CNRS, Rue Bernard Gregory , F-06560 , Valbonne , France
| | - Maria Vladimirova
- L2C , Université de Montpellier, CNRS, Place Eugène Bataillon , F-34095 , Montpellier , France
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