1
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Haque SRU, Michael MH, Zhu J, Zhang Y, Windgätter L, Latini S, Wakefield JP, Zhang GF, Zhang J, Rubio A, Checkelsky JG, Demler E, Averitt RD. Terahertz parametric amplification as a reporter of exciton condensate dynamics. NATURE MATERIALS 2024; 23:796-802. [PMID: 38172546 DOI: 10.1038/s41563-023-01755-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/06/2023] [Indexed: 01/05/2024]
Abstract
Condensates are a hallmark of emergence in quantum materials such as superconductors and charge density waves. Excitonic insulators are an intriguing addition to this library, exhibiting spontaneous condensation of electron-hole pairs. However, condensate observables can be obscured through parasitic coupling to the lattice. Here we employ nonlinear terahertz spectroscopy to disentangle such obscurants through measurement of the quantum dynamics. We target Ta2NiSe5, a putative room-temperature excitonic insulator in which electron-lattice coupling dominates the structural transition (Tc = 326 K), hindering identification of excitonic correlations. A pronounced increase in the terahertz reflectivity manifests following photoexcitation and exhibits a Bose-Einstein condensation-like temperature dependence well below the Tc, suggesting an approach to monitor the exciton condensate dynamics. Nonetheless, dynamic condensate-phonon coupling remains as evidenced by peaks in the enhanced reflectivity spectrum at select infrared-active phonon frequencies, indicating that parametric reflectivity enhancement arises from phonon squeezing. Our results highlight that coherent dynamics can drive parametric stimulated emission.
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Affiliation(s)
- Sheikh Rubaiat Ul Haque
- Department of Physics, University of California San Diego, La Jolla, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | | | - Junbo Zhu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yuan Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - Lukas Windgätter
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
| | - Joshua P Wakefield
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gu-Feng Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
| | - Jingdi Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, USA
- Department of Physics, The Hong Kong University of Science and Technology, Hongkong, China
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter (MPSD), Hamburg, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, New York, NY, USA
| | - Joseph G Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, MA, USA
- Institute for Theoretical Physics, ETH Zürich, Zürich, Switzerland
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, USA.
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2
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Jiang Y, Mi Y, Guo J, Wang Z, Zhang N, Liu B, Luo SN. Multiple coherent amplitude modes and exciton-phonon coupling in quasi-one-dimensional excitonic insulator Ta 2NiSe 5. Phys Chem Chem Phys 2024; 26:15417-15425. [PMID: 38747307 DOI: 10.1039/d4cp00261j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
An excitonic insulator (EI) is an intriguing correlated electronic phase of condensed excitons. Ta2NiSe5 is a model material for investigating condensed excitonic states. Herein, femtosecond pump-probe spectroscopy is used to study the coherent phonon dynamics and associated exciton-phonon coupling in single-crystal Ta2NiSe5. The reflectivity time series consists of exponential decay due to hot carriers and damped oscillations due to the Ag phonon vibration. Given the in-plane anisotropic thermal conductivity of Ta2NiSe5, coherent phonon oscillations are stronger with perpendicular polarization to its quasi-one-dimensional chains. The 1-, 2-, and 4-THz vibration modes show coherent amplitude responses in the EI phase of Ta2NiSe5 with increasing temperature, totally different from those of normal coherent phonons (the 3- and 3.7-THz modes). The amplitude modes at higher frequencies decouple with the EI order parameter at lower temperatures, as supported by theoretical analysis with a model Hamiltonian of the exciton-phonon coupling system. Our work provides valuable insights into the character of the EI order parameter and its coupling to multiple coherent amplitude modes.
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Affiliation(s)
- Yaohua Jiang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, People's Republic of China.
| | - Yang Mi
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, People's Republic of China.
| | - Jia Guo
- Research Center for Life Sciences Computing, Zhejiang Lab, Hangzhou, Zhejiang 311100, People's Republic of China.
| | - Zixuan Wang
- Research Center for Life Sciences Computing, Zhejiang Lab, Hangzhou, Zhejiang 311100, People's Republic of China.
| | - Ning Zhang
- Research Center for Life Sciences Computing, Zhejiang Lab, Hangzhou, Zhejiang 311100, People's Republic of China.
| | - Bo Liu
- Research Center for Novel Computing Sensing and Intelligent Processing, Zhejiang Lab, Hangzhou, Zhejiang 311100, People's Republic of China
| | - Sheng-Nian Luo
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, People's Republic of China.
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3
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Michael MH, Haque SRU, Windgaetter L, Latini S, Zhang Y, Rubio A, Averitt RD, Demler E. Photonic time-crystalline behaviour mediated by phonon squeezing in Ta 2NiSe 5. Nat Commun 2024; 15:3638. [PMID: 38684735 PMCID: PMC11059354 DOI: 10.1038/s41467-024-47855-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 04/11/2024] [Indexed: 05/02/2024] Open
Abstract
Photonic time crystals refer to materials whose dielectric properties are periodic in time, analogous to a photonic crystal whose dielectric properties is periodic in space. Here, we theoretically investigate photonic time-crystalline behaviour initiated by optical excitation above the electronic gap of the excitonic insulator candidate Ta2NiSe5. We show that after electron photoexcitation, electron-phonon coupling leads to an unconventional squeezed phonon state, characterised by periodic oscillations of phonon fluctuations. Squeezing oscillations lead to photonic time crystalline behaviour. The key signature of the photonic time crystalline behaviour is terahertz (THz) amplification of reflectivity in a narrow frequency band. The theory is supported by experimental results on Ta2NiSe5 where photoexcitation with short pulses leads to enhanced THz reflectivity with the predicted features. We explain the key mechanism leading to THz amplification in terms of a simplified electron-phonon Hamiltonian motivated by ab-initio DFT calculations. Our theory suggests that the pumped Ta2NiSe5 is a gain medium, demonstrating that squeezed phonon noise may be used to create THz amplifiers in THz communication applications.
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Affiliation(s)
- Marios H Michael
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany.
| | - Sheikh Rubaiat Ul Haque
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA.
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
| | - Lukas Windgaetter
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
| | - Yuan Zhang
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chausse 149, 22761, Hamburg, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, 162 Fifth Avenue, New York, 10010, NY, USA
| | - Richard D Averitt
- Department of Physics, University of California San Diego, La Jolla, CA, 92093, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
- Institute for Theoretical Physics, ETH Zürich, 8093, Zürich, Switzerland
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4
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Guan M, Chen D, Chen Q, Yao Y, Meng S. Coherent Phonon Assisted Ultrafast Order-Parameter Reversal and Hidden Metallic State in Ta_{2}NiSe_{5}. PHYSICAL REVIEW LETTERS 2023; 131:256503. [PMID: 38181365 DOI: 10.1103/physrevlett.131.256503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 11/20/2023] [Accepted: 12/01/2023] [Indexed: 01/07/2024]
Abstract
The nonequilibrium dynamics during photoinduced insulator-to-metal transition (IMT) in the excitonic insulator (EI) candidate Ta_{2}NiSe_{5} have been investigated, which reproduce the timescale and spectral features of the ultrafast switch and reveal intricate many-body interactions involving multidegrees of freedom. The key role of lattice order parameter (OP) reversal, occurring on a timescale comparable to that of purely electronic processes (<100 fs), is identified. This reversal is enabled by the anharmonic interactions between EI-OP-coupled phonons and the conventional coherent phonons, leading to a modified potential energy landscape and a high-frequency mode up-conversion. The phonon excitation depends on the dynamics of photocarriers distributed around the Fermi level, and thus intertwines with the excitonic quenching and the complete gap collapse. These findings provide a comprehensive understanding of exciton-phonon dynamics in correlated quantum materials.
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Affiliation(s)
- Mengxue Guan
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (Ministry of Education), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Daqiang Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Qing Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yugui Yao
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (Ministry of Education), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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5
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Chen C, Tang W, Chen X, Kang Z, Ding S, Scott K, Wang S, Li Z, Ruff JPC, Hashimoto M, Lu DH, Jozwiak C, Bostwick A, Rotenberg E, da Silva Neto EH, Birgeneau RJ, Chen Y, Louie SG, Wang Y, He Y. Anomalous excitonic phase diagram in band-gap-tuned Ta 2Ni(Se,S) 5. Nat Commun 2023; 14:7512. [PMID: 37980419 PMCID: PMC10657405 DOI: 10.1038/s41467-023-43365-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 11/07/2023] [Indexed: 11/20/2023] Open
Abstract
During a band-gap-tuned semimetal-to-semiconductor transition, Coulomb attraction between electrons and holes can cause spontaneously formed excitons near the zero-band-gap point, or the Lifshitz transition point. This has become an important route to realize bulk excitonic insulators - an insulating ground state distinct from single-particle band insulators. How this route manifests from weak to strong coupling is not clear. In this work, using angle-resolved photoemission spectroscopy (ARPES) and high-resolution synchrotron x-ray diffraction (XRD), we investigate the broken symmetry state across the semimetal-to-semiconductor transition in a leading bulk excitonic insulator candidate system Ta2Ni(Se,S)5. A broken symmetry phase is found to be continuously suppressed from the semimetal side to the semiconductor side, contradicting the anticipated maximal excitonic instability around the Lifshitz transition. Bolstered by first-principles and model calculations, we find strong interband electron-phonon coupling to play a crucial role in the enhanced symmetry breaking on the semimetal side of the phase diagram. Our results not only provide insight into the longstanding debate of the nature of intertwined orders in Ta2NiSe5, but also establish a basis for exploring band-gap-tuned structural and electronic instabilities in strongly coupled systems.
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Affiliation(s)
- Cheng Chen
- Department of Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Weichen Tang
- Physics Department, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Xiang Chen
- Physics Department, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Zhibo Kang
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Shuhan Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC, 29631, USA
| | - Kirsty Scott
- Department of Physics, Yale University, New Haven, CT, 06511, USA
| | - Siqi Wang
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA
| | - Zhenglu Li
- Physics Department, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
| | - Jacob P C Ruff
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, 14853, USA
| | - Makoto Hashimoto
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Dong-Hui Lu
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | | | - Robert J Birgeneau
- Physics Department, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Yulin Chen
- Department of Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom
| | - Steven G Louie
- Physics Department, University of California, Berkeley, CA, 94720, USA.
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA.
| | - Yao Wang
- Department of Physics and Astronomy, Clemson University, Clemson, SC, 29631, USA.
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA.
| | - Yu He
- Department of Applied Physics, Yale University, New Haven, CT, 06511, USA.
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6
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Yoo HM, Korkusinski M, Miravet D, Baldwin KW, West K, Pfeiffer L, Hawrylak P, Ashoori RC. Time, momentum, and energy resolved pump-probe tunneling spectroscopy of two-dimensional electron systems. Nat Commun 2023; 14:7440. [PMID: 37978193 PMCID: PMC10656415 DOI: 10.1038/s41467-023-43268-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/06/2023] [Indexed: 11/19/2023] Open
Abstract
Real-time probing of electrons can uncover intricate relaxation mechanisms and many-body interactions in strongly correlated materials. Here, we introduce time, momentum, and energy resolved pump-probe tunneling spectroscopy (Tr-MERTS). The method allows the injection of electrons at a particular energy and observation of their subsequent decay in energy-momentum space. Using Tr-MERTS, we visualize electronic decay processes, with lifetimes from tens of nanoseconds to tens of microseconds, in Landau levels formed in a GaAs quantum well. Although most observed features agree with simple energy-relaxation, we discovered a splitting in the nonequilibrium energy spectrum in the vicinity of a ferromagnetic state. An exact diagonalization study suggests that the splitting arises from a maximally spin-polarized state with higher energy than a conventional equilibrium skyrmion. Furthermore, we observe time-dependent relaxation of the splitting, which we attribute to single-flipped spins forming skyrmions. These results establish Tr-MERTS as a powerful tool for studying the properties of a 2DES beyond equilibrium.
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Affiliation(s)
- H M Yoo
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - M Korkusinski
- Emerging Technologies Division, National Research Council of Canada, Ottawa, ON, K1A 0R6, Canada
| | - D Miravet
- Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - K W Baldwin
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - K West
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - L Pfeiffer
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - P Hawrylak
- Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - R C Ashoori
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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7
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Duan S, Xia W, Huang C, Wang S, Gu L, Liu H, Xiang D, Qian D, Guo Y, Zhang W. Ultrafast Switching from the Charge Density Wave Phase to a Metastable Metallic State in 1T-TiSe_{2}. PHYSICAL REVIEW LETTERS 2023; 130:226501. [PMID: 37327423 DOI: 10.1103/physrevlett.130.226501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/28/2023] [Accepted: 05/04/2023] [Indexed: 06/18/2023]
Abstract
The ultrafast electronic structures of the charge density wave material 1T-TiSe_{2} were investigated by high-resolution time- and angle-resolved photoemission spectroscopy. We found that the quasiparticle populations drove ultrafast electronic phase transitions in 1T-TiSe_{2} within 100 fs after photoexcitation, and a metastable metallic state, which was significantly different from the equilibrium normal phase, was evidenced far below the charge density wave transition temperature. Detailed time- and pump-fluence-dependent experiments revealed that the photoinduced metastable metallic state was a result of the halted motion of the atoms through the coherent electron-phonon coupling process, and the lifetime of this state was prolonged to picoseconds with the highest pump fluence used in this study. Ultrafast electronic dynamics were well captured by the time-dependent Ginzburg-Landau model. Our work demonstrates a mechanism for realizing novel electronic states by photoinducing coherent motion of atoms in the lattice.
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Affiliation(s)
- Shaofeng Duan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wei Xia
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chaozhi Huang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shichong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lingxiao Gu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Haoran Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dao Xiang
- Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dong Qian
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yanfeng Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wentao Zhang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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8
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Katsumi K, Alekhin A, Souliou SM, Merz M, Haghighirad AA, Le Tacon M, Houver S, Cazayous M, Sacuto A, Gallais Y. Disentangling Lattice and Electronic Instabilities in the Excitonic Insulator Candidate Ta_{2}NiSe_{5} by Nonequilibrium Spectroscopy. PHYSICAL REVIEW LETTERS 2023; 130:106904. [PMID: 36962049 DOI: 10.1103/physrevlett.130.106904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Ta_{2}NiSe_{5} is an excitonic insulator candidate showing the semiconductor or semimetal-to-insulator (SI) transition below T_{c}=326 K. However, since a structural transition accompanies the SI transition, deciphering the role of electronic and lattice degrees of freedom in driving the SI transition has remained controversial. Here, we investigate the photoexcited nonequilibrium state in Ta_{2}NiSe_{5} using pump-probe Raman and photoluminescence spectroscopies. The combined nonequilibrium spectroscopic measurements of the lattice and electronic states reveal the presence of a photoexcited metastable state where the insulating gap is suppressed, but the low-temperature structural distortion is preserved. We conclude that electron correlations play a vital role in the SI transition of Ta_{2}NiSe_{5}.
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Affiliation(s)
- Kota Katsumi
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
| | - Alexandr Alekhin
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
| | - Sofia-Michaela Souliou
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Michael Merz
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Amir-Abbas Haghighirad
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Matthieu Le Tacon
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Sarah Houver
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
| | - Maximilien Cazayous
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
| | - Alain Sacuto
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
| | - Yann Gallais
- Université Paris Cité, CNRS, Matériaux et Phénoménes Quantiques, F-75013 Paris, France
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9
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Nie X, Wu X, Wang Y, Ban S, Lei Z, Yi J, Liu Y, Liu Y. Surface acoustic wave induced phenomena in two-dimensional materials. NANOSCALE HORIZONS 2023; 8:158-175. [PMID: 36448884 DOI: 10.1039/d2nh00458e] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Surface acoustic wave (SAW)-matter interaction provides a fascinating key for inducing and manipulating novel phenomena and functionalities in two-dimensional (2D) materials. The dynamic strain field and piezo-electric field associated with propagating SAWs determine the coherent manipulation and transduction between 2D excitons and phonons. Over the past decade, many intriguing acoustic-induced effects, including the acousto-electric effect, acousto-galvanic effect, acoustic Stark effect, acoustic Hall effect and acoustic exciton transport, have been reported experimentally. However, many more phenomena, such as the valley acousto-electric effect, valley acousto-electric Hall effect and acoustic spin Hall effect, were only theoretically proposed, the experimental verification of which are yet to be achieved. In this minireview, we attempt to overview the recent breakthrough of SAW-induced phenomena covering acoustic charge transport, acoustic exciton transport and modulation, and coherent acoustic phonons. Perspectives on the opportunities of the proposed SAW-induced phenomena, as well as open experimental challenges, are also discussed, attempting to offer some guidelines for experimentalists and theorists to explore the desired exotic properties and boost practical applications of 2D materials.
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Affiliation(s)
- Xuchen Nie
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Xiaoyue Wu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Yang Wang
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Siyuan Ban
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
| | - Zhihao Lei
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, NSW, 2308, Australia
| | - Jiabao Yi
- Global Innovative Centre for Advanced Nanomaterials, College of Engineering, Science and Environment, The University of Newcastle, NSW, 2308, Australia
| | - Ying Liu
- College of Jincheng, Nanjing University of Aeronautics and Astronautics, Nanjing 211156, China.
| | - Yanpeng Liu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China.
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10
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Dong Z, Guo W, Zhang L, Zhang Y, Chen J, Huang L, Chen C, Yang L, Ren Z, Zhang J, Yu W, Li J, Wang L, Zhang K. Excitonic Insulator Enabled Ultrasensitive Terahertz Photodetection with Efficient Low-Energy Photon Harvesting. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2204580. [PMID: 36354190 PMCID: PMC9798984 DOI: 10.1002/advs.202204580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/29/2022] [Indexed: 06/11/2023]
Abstract
Despite the interest toward the terahertz (THz) rapidly increasing, the high-efficient detection of THz photon is not widely available due to the low photoelectric conversion efficiency at this low-energy photon regime. Excitonic insulator (EI) states in emerging materials with anomalous optical transitions and renormalized valence band dispersions render their nontrivial photoresponse, which offers the prospect of harnessing the novel EI properties for the THz detection. Here, an EI-based photodetector is developed for efficient photoelectric conversion in the THz band. High-quality EI material Ta2 NiSe5 is synthesized and the existence of the EI state at room temperature is confirmed. The THz scanning near-field optical microscopy experimentally reveals the strong light-matter interaction in the THz band of EI state in the Ta2 NiSe5 . Benefiting from the strong light-matter interaction, the Ta2 NiSe5 -based photodetectors exhibit superior THz detection performances with a detection sensitivity of ≈42 pW Hz-1/2 and a response time of ≈1.1 µs at 0.1 THz at room temperature. This study provides a new avenue for realizing novel high-performance THz photodetectors by exploiting the emerging EI materials.
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Affiliation(s)
- Zhuo Dong
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Wanlong Guo
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Libo Zhang
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Yan Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Jie Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Luyi Huang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Cheng Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Liu Yang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Zeqian Ren
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Junrong Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Wenzhi Yu
- Songshan Lake Materials LaboratoryDongguanGuangdong523000P. R. China
| | - Jie Li
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Lin Wang
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Kai Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
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11
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Sahimi M, Tahmasebi P. The Potential of Quantum Computing for Geoscience. Transp Porous Media 2022. [DOI: 10.1007/s11242-022-01855-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Dong T, Zhang SJ, Wang NL. Recent Development of Ultrafast Optical Characterizations for Quantum Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2110068. [PMID: 35853841 DOI: 10.1002/adma.202110068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 06/09/2022] [Indexed: 06/15/2023]
Abstract
The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to the visible has opened a new era in the experimental investigation and manipulation of quantum materials. The generation of strong optical field in an ultrashort time scale enables the steering of quantum materials nonadiabatically, inducing novel phenomenon or creating new phases which may not have an equilibrium counterpart. Ultrafast time-resolved optical techniques have provided rich information and played an important role in characterization of the nonequilibrium and nonlinear properties of solid systems. Here, some of the recent progress of ultrafast optical techniques and their applications to the detection and manipulation of physical properties in selected quantum materials are reviewed. Specifically, the new development in the detection of the Higgs mode and photoinduced nonequilibrium response in the study of superconductors by time-resolved terahertz spectroscopy are discussed.
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Affiliation(s)
- Tao Dong
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Si-Jie Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Nan-Lin Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
- Beijing Academy of Quantum Information Sciences, Beijing, 100913, China
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13
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Liu W, Wang Z, Chen Z, Luo J, Li S, Wang L. Algorithm advances and applications of time‐dependent first‐principles simulations for ultrafast dynamics. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1577] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Wen‐Hao Liu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors Chinese Academy of Sciences Beijing China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing China
| | - Zhi Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors Chinese Academy of Sciences Beijing China
| | - Zhang‐Hui Chen
- Materials Science Division Lawrence Berkeley National Laboratory Berkeley California USA
| | - Jun‐Wei Luo
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors Chinese Academy of Sciences Beijing China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing China
- Beijing Academy of Quantum Information Sciences Beijing China
| | - Shu‐Shen Li
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors Chinese Academy of Sciences Beijing China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing China
- Beijing Academy of Quantum Information Sciences Beijing China
| | - Lin‐Wang Wang
- Materials Science Division Lawrence Berkeley National Laboratory Berkeley California USA
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14
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Jog H, Harnagea L, Mele EJ, Agarwal R. Exchange coupling-mediated broken symmetries in Ta 2NiSe 5 revealed from quadrupolar circular photogalvanic effect. SCIENCE ADVANCES 2022; 8:eabl9020. [PMID: 35171672 PMCID: PMC8849275 DOI: 10.1126/sciadv.abl9020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
In low-electron density materials, interactions can lead to highly correlated quantum states of matter. Ta2NiSe5, an excitonic insulator (EI) candidate, exists in a novel broken-symmetry phase below 327 K, characterized by robust exchange interaction and electron-lattice coupling. We study this phase of Ta2NiSe5 using the quadrupole circular photogalvanic effect (QCPGE). Light-matter interaction in Ta2NiSe5 mediated by electric quadrupole/magnetic dipole coupling produces helicity-dependent DC response even with centrosymmetry, making it particularly sensitive to certain other broken symmetries. We show that the exchange interaction in Ta2NiSe5 can lead to a triclinic structure with a broken C2 symmetry. Our results provide an incisive probe of the symmetries of the low-temperature phase of Ta2NiSe5 and add new symmetry constraints to the identification of a strongly correlated EI phase. The high sensitivity of QCPGE to subtle symmetry breaking in centrosymmetric systems will enable its use in studying other complex crystalline systems.
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Affiliation(s)
- Harshvardhan Jog
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Luminita Harnagea
- Department of Physics, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Eugene J. Mele
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ritesh Agarwal
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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15
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Abstract
Advances over the past decade have presented new avenues to achieve control over material properties using intense pulses of electromagnetic radiation, with frequencies ranging from optical (approximately 1 PHz, or 1015 Hz) down to below 1 THz (1012 Hz). Some of these new developments have arisen from new experimental methods to drive and observe transient material properties, while others have emerged from new computational techniques that have made nonequilibrium dynamics more tractable to our understanding. One common issue with most attempts to realize control using electromagnetic pulses is the dissipation of energy, which in many cases poses a limit due to uncontrolled heating and has led to strong interest in using lower frequency and/or highly specific excitations to minimize this effect. Emergent developments in experimental tools using shaped X-ray pulses may in the future offer new possibilities for material control, provided that the issue of heat dissipation can be resolved for higher frequency light. The concept of using appropriately shaped pulses of light to control the properties of materials has a range of potential applications, and relies on an understanding of intricate couplings within the material.![]()
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Affiliation(s)
- Steven L Johnson
- Institute for Quantum Electronics, ETH Zürich, Auguste-Piccard-Hof 1, 8093 Zürich, Switzerland.
- SwissFEL, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
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16
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Bretscher HM, Andrich P, Murakami Y, Golež D, Remez B, Telang P, Singh A, Harnagea L, Cooper NR, Millis AJ, Werner P, Sood AK, Rao A. Imaging the coherent propagation of collective modes in the excitonic insulator Ta 2NiSe 5 at room temperature. SCIENCE ADVANCES 2021; 7:eabd6147. [PMID: 34233871 PMCID: PMC8262811 DOI: 10.1126/sciadv.abd6147] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 05/21/2021] [Indexed: 05/29/2023]
Abstract
Excitonic insulators host a condensate of electron-hole pairs at equilibrium, giving rise to collective many-body effects. Although several materials have emerged as excitonic insulator candidates, evidence of long-range coherence is lacking and the origin of the ordered phase in these systems remains controversial. Here, using ultrafast pump-probe microscopy, we investigate the possible excitonic insulator Ta2NiSe5 Below 328 K, we observe the anomalous micrometer-scale propagation of coherent modes at velocities of ~105 m/s, which we attribute to the hybridization between phonon modes and the phase mode of the condensate. We develop a theoretical framework to support this explanation and propose that electronic interactions provide a substantial contribution to the ordered phase in Ta2NiSe5 These results allow us to understand how the condensate's collective modes transport energy and interact with other degrees of freedom. Our study provides a unique paradigm for the investigation and manipulation of these properties in strongly correlated materials.
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Affiliation(s)
- Hope M Bretscher
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - Paolo Andrich
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
| | - Yuta Murakami
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Denis Golež
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Benjamin Remez
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - Prachi Telang
- Department of Physics, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Anupam Singh
- Department of Physics, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Luminita Harnagea
- Department of Physics, Indian Institute of Science Education and Research, Pune, Maharashtra 411008, India
| | - Nigel R Cooper
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - Andrew J Millis
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Philipp Werner
- Department of Physics, University of Fribourg, Fribourg 1700, Switzerland
| | - A K Sood
- Department of Physics, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
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