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Murakami Y, Uchida K, Koga A, Tanaka K, Werner P. Anomalous Temperature Dependence of High-Harmonic Generation in Mott Insulators. PHYSICAL REVIEW LETTERS 2022; 129:157401. [PMID: 36269969 DOI: 10.1103/physrevlett.129.157401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
We reveal the crucial effect of strong spin-charge coupling on high-harmonic generation (HHG) in Mott insulators. In a system with antiferromagnetic correlations, the HHG signal is drastically enhanced with decreasing temperature, even though the gap increases and the production of charge carriers is suppressed. This anomalous behavior, which has also been observed in recent HHG experiments on Ca_{2}RuO_{4}, originates from a cooperative effect between the spin-charge coupling and the thermal ensemble, as well as the strongly temperature-dependent coherence between charge carriers. We argue that the peculiar temperature dependence of HHG is a generic feature of Mott insulators, which can be controlled via the Coulomb interaction and dimensionality of the system. Our results demonstrate that correlations between different degrees of freedom, which are a characteristic feature of strongly correlated solids, have significant and nontrivial effects on nonlinear optical responses.
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Affiliation(s)
- Yuta Murakami
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
| | - Kento Uchida
- Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Akihisa Koga
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Koichiro Tanaka
- Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Philipp Werner
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
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2
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Innerberger M, Worm P, Prauhart P, Kauch A. Electron-light interaction in nonequilibrium: exact diagonalization for time-dependent Hubbard Hamiltonians. EUROPEAN PHYSICAL JOURNAL PLUS 2020; 135:922. [PMID: 33240742 PMCID: PMC7677296 DOI: 10.1140/epjp/s13360-020-00919-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/04/2020] [Indexed: 06/11/2023]
Abstract
We present a straightforward implementation scheme for solving the time-dependent Schrödinger equation for systems described by the Hubbard Hamiltonian with time-dependent hoppings. The computations can be performed for clusters of up to 14 sites with, in principle, general geometry. For the time evolution, we use the exponential midpoint rule, where the exponentials are computed via a Krylov subspace method, which only uses matrix-vector multiplication. The presented implementation uses standard libraries for constructing sparse matrices and for linear algebra. Therefore, the approach is easy to use on both desktop computers and computational clusters. We apply the method to calculate time evolution of double occupation and nonequilibrium spectral function of a photo-excited Mott-insulator. The results show that not only the double occupation increases due to creation of electron-hole pairs but also the Mott gap becomes partially filled.
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Affiliation(s)
- Michael Innerberger
- Institute of Analysis and Scientific Computing, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien, Austria
| | - Paul Worm
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien, Austria
| | - Paul Prauhart
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien, Austria
| | - Anna Kauch
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien, Austria
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3
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Terashige T, Ono T, Miyamoto T, Morimoto T, Yamakawa H, Kida N, Ito T, Sasagawa T, Tohyama T, Okamoto H. Doublon-holon pairing mechanism via exchange interaction in two-dimensional cuprate Mott insulators. SCIENCE ADVANCES 2019; 5:eaav2187. [PMID: 31187057 PMCID: PMC6555625 DOI: 10.1126/sciadv.aav2187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
Coupling of charge and spin degrees of freedom is a critical feature of correlated electron oxides, as represented by the spin-related mechanism of a Cooper pair under high-T c superconductivity. A doublon-holon pair generated on an antiferromagnetic spin background is also predicted to attract each other via the spin-spin interaction J, similar to a Cooper pair, while its evidence is difficult to obtain experimentally. Here, we investigate such an excitonic effect by electroreflectance spectroscopy using terahertz electric field pulses in undoped cuprates: Nd2CuO4, Sr2CuO2Cl2, and La2CuO4. Analyses of the spectral changes of reflectivity under electric fields reveal that the splitting of odd-parity and even-parity excitons, a measure of doublon-holon binding energy, increases with J. This trend is reproduced by t-J-type model calculations, providing strong evidence of the spin-related doublon-holon pairing. Agreement with the calculations supports the s-wave symmetry of the doublon-holon pair in contrast to the d-wave Cooper pair in doped cuprates.
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Affiliation(s)
- T. Terashige
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Chiba 277-8568, Japan
| | - T. Ono
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - T. Miyamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - T. Morimoto
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - H. Yamakawa
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - N. Kida
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - T. Ito
- National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8565, Japan
| | - T. Sasagawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - T. Tohyama
- Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan
| | - H. Okamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Chiba 277-8568, Japan
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Cao Y, Mazzone DG, Meyers D, Hill JP, Liu X, Wall S, Dean MPM. Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy- and momentum-resolved perspective. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20170480. [PMID: 30929631 PMCID: PMC6452052 DOI: 10.1098/rsta.2017.0480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/31/2018] [Indexed: 05/07/2023]
Abstract
Many remarkable properties of quantum materials emerge from states with intricate coupling between the charge, spin and orbital degrees of freedom. Ultrafast photo-excitation of these materials holds great promise for understanding and controlling the properties of these states. Here, we introduce time-resolved resonant inelastic X-ray scattering (tr-RIXS) as a means of measuring the charge, spin and orbital excitations out of equilibrium. These excitations encode the correlations and interactions that determine the detailed properties of the states generated. After outlining the basic principles and instrumentations of tr-RIXS, we review our first observations of transient antiferromagnetic correlations in quasi two dimensions in a photo-excited Mott insulator and present possible future routes of this fast-developing technique. The increasing number of X-ray free electron laser facilities not only enables tackling long-standing fundamental scientific problems, but also promises to unleash novel inelastic X-ray scattering spectroscopies. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.
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Affiliation(s)
- Y. Cao
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - D. G. Mazzone
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - D. Meyers
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - J. P. Hill
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - X. Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - S. Wall
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| | - M. P. M. Dean
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Miyamoto T, Matsui Y, Terashige T, Morimoto T, Sono N, Yada H, Ishihara S, Watanabe Y, Adachi S, Ito T, Oka K, Sawa A, Okamoto H. Probing ultrafast spin-relaxation and precession dynamics in a cuprate Mott insulator with seven-femtosecond optical pulses. Nat Commun 2018; 9:3948. [PMID: 30258055 PMCID: PMC6158258 DOI: 10.1038/s41467-018-06312-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/23/2018] [Indexed: 11/18/2022] Open
Abstract
A charge excitation in a two-dimensional Mott insulator is strongly coupled with the surrounding spins, which is observed as magnetic-polaron formations of doped carriers and a magnon sideband in the Mott-gap transition spectrum. However, the dynamics related to the spin sector are difficult to measure. Here, we show that pump-probe reflection spectroscopy with seven-femtosecond laser pulses can detect the optically induced spin dynamics in Nd2CuO4, a typical cuprate Mott insulator. The bleaching signal at the Mott-gap transition is enhanced at ~18 fs. This time constant is attributable to the spin-relaxation time during magnetic-polaron formation, which is characterized by the exchange interaction. More importantly, ultrafast coherent oscillations appear in the time evolution of the reflectivity changes, and their frequencies (1400-2700 cm-1) are equal to the probe energy measured from the Mott-gap transition peak. These oscillations can be interpreted as the interference between charge excitations with two magnons originating from charge-spin coupling.
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Affiliation(s)
- T Miyamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - Y Matsui
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - T Terashige
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Chiba, 277-8568, Japan
| | - T Morimoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - N Sono
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - H Yada
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - S Ishihara
- Department of Physics, Tohoku University, Sendai, 980-8578, Japan
| | - Y Watanabe
- Department of Chemistry, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - S Adachi
- Department of Chemistry, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - T Ito
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8565, Ibaraki, Japan
| | - K Oka
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8565, Ibaraki, Japan
| | - A Sawa
- National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8565, Ibaraki, Japan
| | - H Okamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan.
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Chiba, 277-8568, Japan.
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Golež D, Boehnke L, Strand HUR, Eckstein M, Werner P. Nonequilibrium GW+EDMFT: Antiscreening and Inverted Populations from Nonlocal Correlations. PHYSICAL REVIEW LETTERS 2017; 118:246402. [PMID: 28665669 DOI: 10.1103/physrevlett.118.246402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 06/07/2023]
Abstract
We study the dynamics of screening in photodoped Mott insulators with long-ranged interactions using a nonequilibrium implementation of the GW plus extended dynamical mean-field theory formalism. Our study demonstrates that the complex interplay of the injected carriers with bosonic degrees of freedom (charge fluctuations) can result in long-lived transient states with properties that are distinctly different from those of thermal equilibrium states. Systems with strong nonlocal interactions are found to exhibit a self-sustained population inversion of the doublons and holes. This population inversion leads to low-energy antiscreening which can be detected in time-resolved electron-energy-loss spectra.
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Affiliation(s)
- Denis Golež
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Lewin Boehnke
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Hugo U R Strand
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Martin Eckstein
- Max-Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Philipp Werner
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
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Iwano K, Shimoi Y, Miyamoto T, Hata D, Sotome M, Kida N, Horiuchi S, Okamoto H. Ultrafast Photoinduced Electric-Polarization Switching in a Hydrogen-Bonded Ferroelectric Crystal. PHYSICAL REVIEW LETTERS 2017; 118:107404. [PMID: 28339275 DOI: 10.1103/physrevlett.118.107404] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Indexed: 06/06/2023]
Abstract
Croconic acid crystals show proton displacive-type ferroelectricity with a large spontaneous polarization reaching 20 μC/cm^{2}, which originates from the strong coupling of proton and π-electron degrees of freedom. Such a coupling makes us expect a large polarization change by photoirradiations. Optical-pump second-harmonic-generation-probe experiments reveal that a photoexcited croconic-acid crystal loses the ferroelectricity substantially with a maximum quantum efficiency of more than 30 molecules per one absorbed photon. Based on density functional calculations, we theoretically discuss possible pathways toward the formation of a one-dimensional domain with polarization inversion and its recovery process to the ground state by referring to the dynamics of experimentally obtained polarization changes.
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Affiliation(s)
- K Iwano
- Graduate University for Advanced Studies, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan
| | - Y Shimoi
- Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
| | - T Miyamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - D Hata
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - M Sotome
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - N Kida
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - S Horiuchi
- Flexible Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - H Okamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Chiba 277-8568, Japan
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8
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Kogoj J, Mierzejewski M, Bonča J. Nature of Bosonic Excitations Revealed by High-Energy Charge Carriers. PHYSICAL REVIEW LETTERS 2016; 117:227002. [PMID: 27925751 DOI: 10.1103/physrevlett.117.227002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Indexed: 06/06/2023]
Abstract
We address a long-standing problem concerning the origin of bosonic excitations that strongly interact with charge carriers. We show that the time-resolved pump-probe experiments are capable of distinguishing between regular bosonic degrees of freedom, e.g., phonons, and the hard-core bosons, e.g., magnons. The ability of phonon degrees of freedom to absorb essentially an unlimited amount of energy renders relaxation dynamics nearly independent of the absorbed energy or fluence. In contrast, the hard core effects pose limits on the density of energy stored in the bosonic subsystems resulting in a substantial dependence of the relaxation time on the fluence and/or excitation energy. Very similar effects can be observed also in a different setup when the system is driven by multiple pulses.
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Affiliation(s)
- Jan Kogoj
- J. Stefan Institute, 1000 Ljubljana, Slovenia
| | | | - Janez Bonča
- J. Stefan Institute, 1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia
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9
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Relationship between Population Dynamics and the Self-Energy in Driven Non-Equilibrium Systems. ENTROPY 2016. [DOI: 10.3390/e18050180] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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