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Lin T, Chen X, Xu R, Luo J, Zhu H. Ultrafast Polarization-Resolved Phonon Dynamics in Monolayer Semiconductors. NANO LETTERS 2024; 24:10592-10598. [PMID: 39137095 DOI: 10.1021/acs.nanolett.4c02787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Monolayer transition metal dichalcogenide semiconductors exhibit unique valleytronic properties interacting strongly with chiral phonons that break time-reversal symmetry. Here, we observed the ultrafast dynamics of linearly and circularly polarized E'(Γ) phonons at the Brillouin zone center in single-crystalline monolayer WS2, excited by intense, resonant, and polarization-tunable terahertz pulses and probed by time-resolved anti-Stokes Raman spectroscopy. We separated the coherent phonons producing directional sum-frequency generation from the incoherent phonon population emitting scattered photons. The longer incoherent population lifetime than what was expected from coherence lifetime indicates that inhomogeneous broadening and momentum scattering play important roles in phonon decoherence at room temperature. Meanwhile, the faster depolarization rate in circular bases than in linear bases suggests that the eigenstates are linearly polarized due to lattice anisotropy. Our results provide crucial information for improving the lifetime of chiral phonons in two-dimensional materials and potentially facilitate dynamic control of spin-orbital polarizations in quantum materials.
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Affiliation(s)
- Tong Lin
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Xiaotong Chen
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Rui Xu
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Jiaming Luo
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Hanyu Zhu
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
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2
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Sun C, Zhou H, Sheng T, Li S, Zhu H. Ultrafast Interlayer Charge Transfer Outcompeting Intralayer Valley Relaxation in Few-Layer 2D Heterostructures. ACS NANO 2024; 18:931-938. [PMID: 38154000 DOI: 10.1021/acsnano.3c09681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2023]
Abstract
While 2D transition metal dichalcogenides (TMDs) feature interesting layer-tunable multivalley band structures, their preeminent role in determining the photoexcitation charge transfer dynamics in 2D heterostructures (HSs) is yet to be unraveled, as previous charge transfer studies on TMD HSs have been mostly focused on monolayers with a direct bandgap at the K valley. By ultrafast transient absorption spectroscopy and deliberately designed few-layer WSe2/WS2 HSs, we have observed an ultrafast interlayer electron transfer from photoexcited few-layer WSe2 to WS2, prior to intralayer relaxation to lower lying dark valleys. More interestingly, we have identified an unconventional ∼0.5 ps electron back-transfer process after the initial interlayer electron transfer in HSs with WSe2 layers ≥ 3, regenerating indirect intralayer excitons. The result reveals an ielectron and valley relaxation pathway mediated by interlayer charge transfer in 2D HSs, faster than intralayer relaxation. It also sheds light on the origin of generally observed robust ultrafast interlayer charge transfer in TMD HSs and provides guidance toward optoelectronic and valleytronic devices using few-layer TMDs.
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Affiliation(s)
- Cheng Sun
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, China, 310027
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, Zhejiang, China, 311215
| | - Hongzhi Zhou
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, China, 310027
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, Zhejiang, China, 311215
| | - Tianyu Sheng
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, China, 310027
| | - Shuangshuang Li
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, China, 310027
| | - Haiming Zhu
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, China, 310027
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, Zhejiang, China, 311215
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3
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Tan QH, Li YM, Lai JM, Sun YJ, Zhang Z, Song F, Robert C, Marie X, Gao W, Tan PH, Zhang J. Quantum interference between dark-excitons and zone-edged acoustic phonons in few-layer WS 2. Nat Commun 2023; 14:88. [PMID: 36604415 PMCID: PMC9816112 DOI: 10.1038/s41467-022-35714-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/15/2022] [Indexed: 01/07/2023] Open
Abstract
Fano resonance which describes a quantum interference between continuum and discrete states, provides a unique method for studying strongly interacting physics. Here, we report a Fano resonance between dark excitons and zone-edged acoustic phonons in few-layer WS2 by using the resonant Raman technique. The discrete phonons with large momentum at the M-point of the Brillouin zone and the continuum dark exciton states related to the optically forbidden transition at K and Q valleys are coupled by the exciton-phonon interactions. We observe rich Fano resonance behaviors across layers and modes defined by an asymmetry-parameter q: including constructive interference with two mirrored asymmetry Fano peaks (weak coupling, q > 1 and q < - 1), and destructive interference with Fano dip (strong coupling, ∣q∣ < < 1). Our results provide new insight into the exciton-phonon quantum interference in two-dimensional semiconductors, where such interferences play a key role in their transport, optical, and thermodynamic properties.
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Affiliation(s)
- Qing-Hai Tan
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore
| | - Yun-Mei Li
- grid.12955.3a0000 0001 2264 7233Department of Physics, Xiamen University, Xiamen, 361005 China
| | - Jia-Min Lai
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yu-Jia Sun
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Zhe Zhang
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Feilong Song
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Cedric Robert
- grid.462768.90000 0004 0383 4043University of Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse, France
| | - Xavier Marie
- grid.462768.90000 0004 0383 4043University of Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse, France
| | - Weibo Gao
- grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore ,grid.59025.3b0000 0001 2224 0361The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, 637371 Singapore, Singapore ,grid.4280.e0000 0001 2180 6431Centre for Quantum Technologies, National University of Singapore, Singapore, 117543 Singapore
| | - Ping-Heng Tan
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jun Zhang
- grid.9227.e0000000119573309State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, 100083 China ,grid.410726.60000 0004 1797 8419Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.410726.60000 0004 1797 8419CAS Center of Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100049 China
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Datta B, Khatoniar M, Deshmukh P, Thouin F, Bushati R, De Liberato S, Cohen SK, Menon VM. Highly nonlinear dipolar exciton-polaritons in bilayer MoS 2. Nat Commun 2022; 13:6341. [PMID: 36284098 PMCID: PMC9596727 DOI: 10.1038/s41467-022-33940-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/07/2022] [Indexed: 11/24/2022] Open
Abstract
Realizing nonlinear optical response in the low photon density limit in solid-state systems has been a long-standing challenge. Semiconductor microcavities in the strong coupling regime hosting exciton-polaritons have emerged as attractive candidates in this context. However, the weak interaction between these quasiparticles has been a hurdle in this quest. Dipolar excitons provide an attractive strategy to overcome this limitation but are often hindered by their weak oscillator strength. The interlayer dipolar excitons in naturally occurring homobilayer MoS2 alleviates this issue owing to their formation via hybridization of interlayer charge transfer exciton with intralayer B exciton. Here we demonstrate the formation of dipolar exciton polaritons in bilayer MoS2 resulting in unprecedented nonlinear interaction strengths. A ten-fold increase in nonlinearity is observed for the interlayer dipolar excitons compared to the conventional A excitons. These highly nonlinear dipolar polaritons will likely be a frontrunner in the quest for solid-state quantum nonlinear devices. Dipolar excitons enable large nonlinear interaction but are usually hampered by their weak oscillator strength. Here, the authors demonstrate the strong light-matter coupling of interlayer dipolar excitons having unusually large oscillator strength in bilayer MoS2 resulting in highly nonlinear dipolar polaritons.
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Affiliation(s)
- Biswajit Datta
- grid.254250.40000 0001 2264 7145Department of Physics, City College of New York, New York, NY USA
| | - Mandeep Khatoniar
- grid.254250.40000 0001 2264 7145Department of Physics, City College of New York, New York, NY USA ,grid.253482.a0000 0001 0170 7903Department of Physics, Graduate Center of the City University of New York (CUNY), New York, NY USA
| | - Prathmesh Deshmukh
- grid.254250.40000 0001 2264 7145Department of Physics, City College of New York, New York, NY USA ,grid.253482.a0000 0001 0170 7903Department of Physics, Graduate Center of the City University of New York (CUNY), New York, NY USA
| | - Félix Thouin
- grid.183158.60000 0004 0435 3292Department of Engineering Physics, École Polytechnique de Montréal, Montréal, QC Canada
| | - Rezlind Bushati
- grid.254250.40000 0001 2264 7145Department of Physics, City College of New York, New York, NY USA ,grid.253482.a0000 0001 0170 7903Department of Physics, Graduate Center of the City University of New York (CUNY), New York, NY USA
| | - Simone De Liberato
- grid.5491.90000 0004 1936 9297School of Physics and Astronomy, University of Southampton, Southampton, UK
| | - Stephane Kena Cohen
- grid.183158.60000 0004 0435 3292Department of Engineering Physics, École Polytechnique de Montréal, Montréal, QC Canada
| | - Vinod M. Menon
- grid.254250.40000 0001 2264 7145Department of Physics, City College of New York, New York, NY USA ,grid.253482.a0000 0001 0170 7903Department of Physics, Graduate Center of the City University of New York (CUNY), New York, NY USA
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First-Principles Study of the Optical Properties of TMDC/Graphene Heterostructures. PHOTONICS 2022. [DOI: 10.3390/photonics9060387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The transition-metal dichalcogenide (TMDC) in the family of MX2 (M=Mo,W; X=S,Se) and the graphene (Gr) monolayer are an atomically thin semiconductor and a semimetal, respectively. The monolayer MX2 has been discovered as a new class of semiconductors for electronics and optoelectronics applications. Because of the hexagonal lattice structure of both materials, MX2 and Gr are often combined with each other to generate van der Waals heterostructures. Here, the MX2/Gr heterostructures are investigated theoretically based on density functional theory (DFT). The electronic structure and the optical properties of four different MX2/Gr heterostructures are computed. We systematically compare these MX2/Gr heterostructures for their complex permittivity, absorption coefficient, reflectivity and refractive index.
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Hader J, Neuhaus J, Moloney JV, Koch SW. On the importance of electron-electron and electron-phonon scatterings and energy renormalizations during carrier relaxation in monolayer transition-metal dichalcogenides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:285601. [PMID: 35453129 DOI: 10.1088/1361-648x/ac699e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
Anab initiobased fully microscopic many-body approach is used to study the carrier relaxation dynamics in monolayer transition-metal dichalcogenides. Bandstructures and wavefunctions as well as phonon energies and coupling matrix elements are calculated using density functional theory. The resulting dipole and Coulomb matrix elements are implemented in the Dirac-Bloch equations to calculate carrier-carrier and carrier-phonon scatterings throughout the whole Brillouin zone (BZ). It is shown that carrier scatterings lead to a relaxation into hot quasi-Fermi distributions on a single femtosecond timescale. Carrier cool down and inter-valley transitions are mediated by phonon scatterings on a picosecond timescale. Strong, density-dependent energy renormalizations are shown to be valley-dependent. For MoTe2, MoSe2and MoS2the change of energies with occupation is found to be about 50% stronger in the Σ and Λ side valleys than in theKandK' valleys. However, for realistic carrier densities, the materials always maintain their direct bandgap at theKpoints of the BZ.
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Affiliation(s)
- Jörg Hader
- Wyant College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721, United States of America
| | - Josefine Neuhaus
- Department of Physics and Material Sciences Center, Philipps-University Marburg, Renthof 5, 35032 Marburg, Germany
| | - Jerome V Moloney
- Wyant College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721, United States of America
| | - Stephan W Koch
- Department of Physics and Material Sciences Center, Philipps-University Marburg, Renthof 5, 35032 Marburg, Germany
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