1
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Dufresne SKY, Zhdanovich S, Michiardi M, Guislain BG, Zonno M, Mazzotti V, O'Brien L, Kung S, Levy G, Mills AK, Boschini F, Jones DJ, Damascelli A. A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:033907. [PMID: 38517258 DOI: 10.1063/5.0176170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved μ-ARPES). With a combination of tunable spatial resolution down to ∼11 μm, high energy resolution (∼11 meV), near-transform-limited temporal resolution (∼280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm2, this time-resolved μ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved μ-ARPES on a ∼30 μm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.
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Affiliation(s)
- S K Y Dufresne
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - S Zhdanovich
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Michiardi
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - B G Guislain
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Zonno
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - V Mazzotti
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - L O'Brien
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - S Kung
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - G Levy
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A K Mills
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - F Boschini
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Centre Énergie Matériaux Télécommunications, Institut National de la Recherche Scientifique, Varennes, Québec J3X 1S2, Canada
| | - D J Jones
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A Damascelli
- Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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2
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Horn-von Hoegen M. Structural dynamics at surfaces by ultrafast reflection high-energy electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:021301. [PMID: 38495951 PMCID: PMC10942804 DOI: 10.1063/4.0000234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/13/2024] [Indexed: 03/19/2024]
Abstract
Many fundamental processes of structural changes at surfaces occur on a pico- or femtosecond timescale. In order to study such ultrafast processes, we have combined modern surface science techniques with fs-laser pulses in a pump-probe scheme. Grazing incidence of the electrons ensures surface sensitivity in ultrafast reflection high-energy electron diffraction (URHEED). Utilizing the Debye-Waller effect, we studied the nanoscale heat transport from an ultrathin film through a hetero-interface or the damping of vibrational excitations in monolayer adsorbate systems on the lower ps-timescale. By means of spot profile analysis, the different cooling rates of epitaxial Ge nanostructures of different size and strain state were determined. The excitation and relaxation dynamics of a driven phase transition far away from thermal equilibrium is demonstrated using the In-induced (8 × 2) reconstruction on Si(111). This Peierls-distorted surface charge density wave system exhibits a discontinuous phase transition of first order at 130 K from a (8 × 2) insulating ground state to (4 × 1) metallic excited state. Upon excitation by a fs-laser pulse, this structural phase transition is non-thermally driven in only 700 fs into the excited state. A small barrier of 40 meV hinders the immediate recovery of the ground state, and the system is found in a metastable supercooled state for up to few nanoseconds.
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Affiliation(s)
- Michael Horn-von Hoegen
- Department of Physics and Center for Nanointegration CENIDE, University of Duisburg-Essen, Lotharstrasse. 1, 47057 Duisburg, Germany
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3
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Maklar J, Sarkar J, Dong S, Gerasimenko YA, Pincelli T, Beaulieu S, Kirchmann PS, Sobota JA, Yang S, Leuenberger D, Moore RG, Shen ZX, Wolf M, Mihailovic D, Ernstorfer R, Rettig L. Coherent light control of a metastable hidden state. SCIENCE ADVANCES 2023; 9:eadi4661. [PMID: 38000022 PMCID: PMC10672165 DOI: 10.1126/sciadv.adi4661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 10/24/2023] [Indexed: 11/26/2023]
Abstract
Metastable phases present a promising route to expand the functionality of complex materials. Of particular interest are light-induced metastable phases that are inaccessible under equilibrium conditions, as they often host new, emergent properties switchable on ultrafast timescales. However, the processes governing the trajectories to such hidden phases remain largely unexplored. Here, using time- and angle-resolved photoemission spectroscopy, we investigate the ultrafast dynamics of the formation of a hidden quantum state in the layered dichalcogenide 1T-TaS2 upon photoexcitation. Our results reveal the nonthermal character of the transition governed by a collective charge-density-wave excitation. Using a double-pulse excitation of the structural mode, we show vibrational coherent control of the phase-transition efficiency. Our demonstration of exceptional control, switching speed, and stability of the hidden state are key for device applications at the nexus of electronics and photonics.
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Affiliation(s)
- Julian Maklar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Jit Sarkar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Shuo Dong
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Yaroslav A. Gerasimenko
- Department of Complex Matter, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Center of Excellence on Nanoscience and Nanotechnology – Nanocenter (CENN Nanocenter), Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Tommaso Pincelli
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Samuel Beaulieu
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Patrick S. Kirchmann
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Jonathan A. Sobota
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Shuolong Yang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Dominik Leuenberger
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Robert G. Moore
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Zhi-Xun Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Martin Wolf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Dragan Mihailovic
- Department of Complex Matter, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Center of Excellence on Nanoscience and Nanotechnology – Nanocenter (CENN Nanocenter), Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Ralph Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Laurenz Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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4
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Azoury D, von Hoegen A, Su Y, Oh KH, Holder T, Tan H, Ortiz BR, Capa Salinas A, Wilson SD, Yan B, Gedik N. Direct observation of the collective modes of the charge density wave in the kagome metal CsV 3Sb 5. Proc Natl Acad Sci U S A 2023; 120:e2308588120. [PMID: 37748057 PMCID: PMC10556638 DOI: 10.1073/pnas.2308588120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/31/2023] [Indexed: 09/27/2023] Open
Abstract
A recently discovered group of kagome metals AV[Formula: see text]Sb[Formula: see text] (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this charge-ordered parent phase is crucial for deciphering the entire phase diagram. However, the mechanism of the charge density wave is still controversial, and its primary source of fluctuations-the collective modes-has not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV[Formula: see text]Sb[Formula: see text] and record the resulting dynamics using femtosecond angle-resolved photoemission. We resolve the melting time of the charge order and directly observe its amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time. These observations together with ab initio calculations provide clear evidence for a structural rather than electronic mechanism of the charge density wave. Our findings pave the way for a better understanding of the unconventional phases hosted on the kagome lattice.
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Affiliation(s)
- Doron Azoury
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Alexander von Hoegen
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Yifan Su
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Kyoung Hun Oh
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Tobias Holder
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Hengxin Tan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Brenden R. Ortiz
- Materials Department, University of California, Santa Barbara, CA93106
| | | | - Stephen D. Wilson
- Materials Department, University of California, Santa Barbara, CA93106
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Nuh Gedik
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
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5
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Jung J, Jin KH, Kim J, Yeom HW. Control over a Wide Phase Diagram of 2D Correlated Electrons by Surface Doping; K/1 T-TaS 2. NANO LETTERS 2023; 23:8029-8034. [PMID: 37651727 DOI: 10.1021/acs.nanolett.3c02003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
We demonstrate the systematic tuning of a trivial insulator into a Mott insulator and a Mott insulator into a correlated metallic and a pseudogap state, which emerge in a quasi-two-dimensional electronic system of 1T-TaS2 through strong electron correlation. The band structure evolution is investigated upon surface doping by alkali adsorbates for two distinct phases occurring at around 220 and 10 K by angle-resolved photoelectron spectroscopy. We find contrasting behaviors upon doping that corroborate the fundamental difference of two electronic states: while the antibonding state of the spin-singlet insulator at 10 K is partially occupied to produce an emerging Mott insulating state, the presumed Mott insulating state at 220 K evolves into a correlated metallic state and then a pseudogap state. The work indicates that surface doping onto correlated 2D materials can be a powerful tool to systematically engineer a wide range of correlated electronic phases.
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Affiliation(s)
- Jiwon Jung
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Kyung-Hwan Jin
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Jaeyoung Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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6
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Pan X, Yang T, Bai H, Peng J, Li L, Jing F, Qiu H, Liu H, Hu Z. Controllable Synthesis and Charge Density Wave Phase Transitions of Two-Dimensional 1T-TaS 2 Crystals. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111806. [PMID: 37299709 DOI: 10.3390/nano13111806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/02/2023] [Accepted: 06/02/2023] [Indexed: 06/12/2023]
Abstract
1T-TaS2 has attracted much attention recently due to its abundant charge density wave phases. In this work, high-quality two-dimensional 1T-TaS2 crystals were successfully synthesized by a chemical vapor deposition method with controllable layer numbers, confirmed by the structural characterization. Based on the as-grown samples, their thickness-dependency nearly commensurate charge density wave/commensurate charge density wave phase transitions was revealed by the combination of the temperature-dependent resistance measurements and Raman spectra. The phase transition temperature increased with increasing thickness, but no apparent phase transition was found on the 2~3 nm thick crystals from temperature-dependent Raman spectra. The transition hysteresis loops due to temperature-dependent resistance changes of 1T-TaS2 can be used for memory devices and oscillators, making 1T-TaS2 a promising material for various electronic applications.
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Affiliation(s)
- Xiaoguang Pan
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Tianwen Yang
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Hangxin Bai
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Jiangbo Peng
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Lujie Li
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Fangli Jing
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Hailong Qiu
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Hongjun Liu
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
| | - Zhanggui Hu
- Tianjin Key Laboratory of Functional Crystal Materials, Institute of Functional Crystals, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China
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7
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Kim TJ, Jeong MY, Han MJ. First principles investigation of screened Coulomb interaction and electronic structure of low-temperature phase TaS 2. iScience 2023; 26:106681. [PMID: 37250339 PMCID: PMC10214477 DOI: 10.1016/j.isci.2023.106681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/28/2023] [Accepted: 04/12/2023] [Indexed: 05/31/2023] Open
Abstract
By means of ab initio computation schemes, we examine the electronic screening, Coulomb interaction strength, and the electronic structure of a quantum spin liquid candidate monolayer TaS2 in its low-temperature commensurate charge-density-wave phase. Not only local (U) but non-local (V) correlations are estimated within random phase approximation based on two different screening models. Using GW + EDMFT (GW plus extended dynamical mean-field theory) method, we investigate the detailed electronic structure by increasing the level of non-local approximation from DMFT (V=0) to EDMFT and GW + EDMFT.
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Affiliation(s)
- Taek Jung Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Min Yong Jeong
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Myung Joon Han
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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8
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Erpenbeck A, Gull E, Cohen G. Quantum Monte Carlo Method in the Steady State. PHYSICAL REVIEW LETTERS 2023; 130:186301. [PMID: 37204908 DOI: 10.1103/physrevlett.130.186301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/07/2022] [Accepted: 04/07/2023] [Indexed: 05/21/2023]
Abstract
We present a numerically exact steady-state inchworm Monte Carlo method for nonequilibrium quantum impurity models. Rather than propagating an initial state to long times, the method is directly formulated in the steady state. This eliminates any need to traverse the transient dynamics and grants access to a much larger range of parameter regimes at vastly reduced computational costs. We benchmark the method on equilibrium Green's functions of quantum dots in the noninteracting limit and in the unitary limit of the Kondo regime. We then consider correlated materials described with dynamical mean field theory and driven away from equilibrium by a bias voltage. We show that the response of a correlated material to a bias voltage differs qualitatively from the splitting of the Kondo resonance observed in bias-driven quantum dots.
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Affiliation(s)
- A Erpenbeck
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - E Gull
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - G Cohen
- The Raymond and Beverley Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 6997801, Israel
- School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel
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9
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Sayers CJ, Cerullo G, Zhang Y, Sanders CE, Chapman RT, Wyatt AS, Chatterjee G, Springate E, Wolverson D, Da Como E, Carpene E. Exploring the Charge Density Wave Phase of 1T-TaSe_{2}: Mott or Charge-Transfer Gap? PHYSICAL REVIEW LETTERS 2023; 130:156401. [PMID: 37115877 DOI: 10.1103/physrevlett.130.156401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/29/2022] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
1T-TaSe_{2} is widely believed to host a Mott metal-insulator transition in the charge density wave (CDW) phase according to the spectroscopic observation of a band gap that extends across all momentum space. Previous investigations inferred that the occurrence of the Mott phase is limited to the surface only of bulk specimens, but recent analysis on thin samples revealed that the Mott-like behavior, observed in the monolayer, is rapidly suppressed with increasing thickness. Here, we report combined time- and angle-resolved photoemission spectroscopy and theoretical investigations of the electronic structure of 1T-TaSe_{2}. Our experimental results confirm the existence of a state above E_{F}, previously ascribed to the upper Hubbard band, and an overall band gap of ∼0.7 eV at Γ[over ¯]. However, supported by density functional theory calculations, we demonstrate that the origin of this state and the gap rests on band structure modifications induced by the CDW phase alone, without the need for Mott correlation effects.
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Affiliation(s)
- C J Sayers
- Dipartimento di Fisica, Politecnico di Milano, Milan 20133, Italy
| | - G Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Milan 20133, Italy
| | - Y Zhang
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - C E Sanders
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - R T Chapman
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - A S Wyatt
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - G Chatterjee
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - E Springate
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - D Wolverson
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - E Da Como
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - E Carpene
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Milan 20133, Italy
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10
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Liu WH, Gu YX, Wang Z, Li SS, Wang LW, Luo JW. Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge-Density-Wave Transition. PHYSICAL REVIEW LETTERS 2023; 130:146901. [PMID: 37084436 DOI: 10.1103/physrevlett.130.146901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 02/16/2023] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
In stark contrast to the conventional charge density wave (CDW) materials, the one-dimensional CDW on the In/Si(111) surface exhibits immediate damping of the CDW oscillation during the photoinduced phase transition. Here, we successfully reproduce the experimental observation of the photoinduced CDW transition on the In/Si(111) surface by performing real-time time-dependent density functional theory (rt-TDDFT) simulations. We show that photoexcitation promotes valence electrons from the Si substrate to the empty surface bands composed primarily of the covalent p-p bonding states of the long In-In bonds. Such photoexcitation generates interatomic forces to shorten the long In-In bonds and thus drives the structural transition. After the structural transition, these surface bands undergo a switch among different In-In bonds, causing a rotation of the interatomic forces by about π/6 and thus quickly damping the oscillations in feature CDW modes. These findings provide a deeper understanding of photoinduced phase transitions.
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Affiliation(s)
- Wen-Hao Liu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu-Xiang Gu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhi Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Shu-Shen Li
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lin-Wang Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Jun-Wei Luo
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Rajpurohit S, Simoni J, Tan LZ. Photo-induced phase-transitions in complex solids. NANOSCALE ADVANCES 2022; 4:4997-5008. [PMID: 36504738 PMCID: PMC9680828 DOI: 10.1039/d2na00481j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/01/2022] [Indexed: 06/17/2023]
Abstract
Photo-induced phase-transitions (PIPTs) driven by highly cooperative interactions are of fundamental interest as they offer a way to tune and control material properties on ultrafast timescales. Due to strong correlations and interactions, complex quantum materials host several fascinating PIPTs such as light-induced charge density waves and ferroelectricity and have become a desirable setting for studying these PIPTs. A central issue in this field is the proper understanding of the underlying mechanisms driving the PIPTs. As these PIPTs are highly nonlinear processes and often involve multiple time and length scales, different theoretical approaches are often needed to understand the underlying mechanisms. In this review, we present a brief overview of PIPTs realized in complex materials, followed by a discussion of the available theoretical methods with selected examples of recent progress in understanding of the nonequilibrium pathways of PIPTs.
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Affiliation(s)
| | - Jacopo Simoni
- Molecular Foundry, Lawrence Berkeley National Laboratory USA
| | - Liang Z Tan
- Molecular Foundry, Lawrence Berkeley National Laboratory USA
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12
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Zhong H, Bao C, Lin T, Zhou S, Zhou S. A newly designed femtosecond KBe 2BO 3F 2 device with pulse duration down to 55 fs for time- and angle-resolved photoemission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113910. [PMID: 36461493 DOI: 10.1063/5.0106864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/15/2022] [Indexed: 06/17/2023]
Abstract
Developing a widely tunable vacuum ultraviolet (VUV) source with a sub-100 fs pulse duration is critical for ultrafast pump-probe techniques such as time- and angle-resolved photoemission spectroscopy (TrARPES). While a tunable probe source with a photon energy of 5.3-7.0 eV has been recently implemented for TrARPES by using a KBe2BO3F2 (KBBF) device, the time resolution of 280-320 fs is still not ideal, which is mainly limited by the duration of the VUV probe pulse generated by the KBBF device. Here, by designing a new KBBF device, which is specially optimized for fs applications, an optimum pulse duration of 55 fs is obtained after systematic diagnostics and optimization. More importantly, a high time resolution of 81-95 fs is achieved for TrARPES measurements covering the probe photon energy range of 5.3-7.0 eV, making it particularly useful for investigating the ultrafast dynamics of quantum materials. Our work extends the application of the KBBF device to ultrafast pump-probe techniques with the advantages of both a widely tunable VUV source and ultimate time resolution.
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Affiliation(s)
- Haoyuan Zhong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Changhua Bao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Tianyun Lin
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shaohua Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shuyun Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
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13
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Lee D, Jin KH, Liu F, Yeom HW. Tunable Mott Dirac and Kagome Bands Engineered on 1 T-TaS 2. NANO LETTERS 2022; 22:7902-7909. [PMID: 36162122 DOI: 10.1021/acs.nanolett.2c02866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Strongly interacting electrons in hexagonal and kagome lattices exhibit rich phase diagrams of exotic quantum states, including superconductivity and correlated topological orders. However, material realizations of these electronic states have been scarce in nature or by design. Here, we theoretically propose an approach to realize artificial lattices by metal adsorption on a 2D Mott insulator 1T-TaS2. Alkali, alkaline-earth, and group 13 metal atoms are deposited in (√3 × √3)R30° and 2 × 2 TaS2 superstructures of honeycomb- and kagome-lattice symmetries exhibiting Dirac and kagome bands, respectively. The strong electron correlation of 1T-TaS2 drives the honeycomb and kagome systems into correlated topological phases described by Kane-Mele-Hubbard and kagome-Hubbard models. We further show that the 2/3 or 3/4 band filling of Mott Dirac and flat bands can be achieved with a proper concentration of Mg adsorbates. Our proposal may be readily implemented in experiments, offering an attractive condensed-matter platform to exploit the interplay of correlated topological order and superconductivity.
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Affiliation(s)
- Dongheon Lee
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Kyung-Hwan Jin
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
| | - Feng Liu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Republic of Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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14
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Huber M, Lin Y, Dale N, Sailus R, Tongay S, Kaindl RA, Lanzara A. Revealing the order parameter dynamics of 1T-TiSe[Formula: see text] following optical excitation. Sci Rep 2022; 12:15860. [PMID: 36151110 PMCID: PMC9508156 DOI: 10.1038/s41598-022-19319-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 08/26/2022] [Indexed: 11/09/2022] Open
Abstract
The formation of a charge density wave state is characterized by an order parameter. The way it is established provides unique information on both the role that correlation plays in driving the charge density wave formation and the mechanism behind its formation. Here we use time and angle resolved photoelectron spectroscopy to optically perturb the charge-density phase in 1T-TiSe[Formula: see text] and follow the recovery of its order parameter as a function of energy, momentum and excitation density. Our results reveal that two distinct orders contribute to the gap formation, a CDW order and pseudogap-like order, manifested by an overall robustness to optical excitation. A detailed analysis of the magnitude of the the gap as a function of excitation density and delay time reveals the excitonic long-range nature of the CDW gap and the short-range Jahn-Teller character of the pseudogap order. In contrast to the gap, the intensity of the folded Se[Formula: see text]* band can only give access to the excitonic order. These results provide new information into the the long standing debate on the origin of the gap in TiSe[Formula: see text] and place it in the same context of other quantum materials where a pseudogap phase appears to be a precursor of long-range order.
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Affiliation(s)
- Maximilian Huber
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Yi Lin
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Nicholas Dale
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Physics Department, University of California Berkeley, Berkeley, CA 94720 USA
| | - Renee Sailus
- Materials Science and Engineering Department, Arizona State University, Phoenix, AZ 85281 USA
| | - Sefaattin Tongay
- Materials Science and Engineering Department, Arizona State University, Phoenix, AZ 85281 USA
| | - Robert A. Kaindl
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Department of Physics and CXFEL Labs, Arizona State University, Phoenix, AZ 85287 USA
| | - Alessandra Lanzara
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Physics Department, University of California Berkeley, Berkeley, CA 94720 USA
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15
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Heber M, Wind N, Kutnyakhov D, Pressacco F, Arion T, Roth F, Eberhardt W, Rossnagel K. Multispectral time-resolved energy-momentum microscopy using high-harmonic extreme ultraviolet radiation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:083905. [PMID: 36050085 DOI: 10.1063/5.0091003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
A 790-nm-driven high-harmonic generation source with a repetition rate of 6 kHz is combined with a toroidal-grating monochromator and a high-detection-efficiency photoelectron time-of-flight momentum microscope to enable time- and momentum-resolved photoemission spectroscopy over a spectral range of 23.6-45.5 eV with sub-100 fs time resolution. Three-dimensional (3D) Fermi surface mapping is demonstrated on graphene-covered Ir(111) with energy and momentum resolutions of ≲100 meV and ≲0.1 Å-1, respectively. The tabletop experiment sets the stage for measuring the kz-dependent ultrafast dynamics of 3D electronic structure, including band structure, Fermi surface, and carrier dynamics in 3D materials as well as 3D orbital dynamics in molecular layers.
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Affiliation(s)
- Michael Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Nils Wind
- Institut für Experimental Physik, Universität Hamburg, 22761 Hamburg, Germany
| | | | | | - Tiberiu Arion
- Centre for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Friedrich Roth
- Institute of Experimental Physics, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Wolfgang Eberhardt
- Centre for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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16
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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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17
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Petocchi F, Nicholson CW, Salzmann B, Pasquier D, Yazyev OV, Monney C, Werner P. Mott versus Hybridization Gap in the Low-Temperature Phase of 1T-TaS_{2}. PHYSICAL REVIEW LETTERS 2022; 129:016402. [PMID: 35841569 DOI: 10.1103/physrevlett.129.016402] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/07/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
We address the long-standing problem of the ground state of 1T-TaS_{2} by computing the correlated electronic structure of stacked bilayers using the GW+EDMFT method. Depending on the surface termination, the semi-infinite uncorrelated system is either band insulating or exhibits a metallic surface state. For realistic values of the on-site and inter-site interactions, a Mott gap opens in the surface state, but it is smaller than the gap originating from the bilayer structure. Our results are consistent with recent scanning tunneling spectroscopy measurements for different terminating layers, and with our own photoemission measurements, which indicate the coexistence of spatial regions with different gaps in the electronic spectrum. By comparison to exact diagonalization data, we clarify the interplay between Mott insulating and band insulating behavior in this archetypal layered system.
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Affiliation(s)
- Francesco Petocchi
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Christopher W Nicholson
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
- Fritz-Haber-Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Bjoern Salzmann
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Diego Pasquier
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Oleg V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Claude Monney
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Philipp Werner
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
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18
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Düvel M, Merboldt M, Bange JP, Strauch H, Stellbrink M, Pierz K, Schumacher HW, Momeni D, Steil D, Jansen GSM, Steil S, Novko D, Mathias S, Reutzel M. Far-from-Equilibrium Electron-Phonon Interactions in Optically Excited Graphene. NANO LETTERS 2022; 22:4897-4904. [PMID: 35649249 DOI: 10.1021/acs.nanolett.2c01325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a strong optical excitation, where the electron and phonon systems can be significantly perturbed and the quasiparticle distributions cannot be described with equilibrium functions. In this work, we use time- and angle-resolved photoelectron spectroscopy to study such far-from-equilibrium many-body interactions for the prototypical material graphene. In accordance with theoretical simulations, we find remarkable transient renormalizations of the quasiparticle self-energy caused by the photoinduced nonequilibrium conditions. These observations can be understood by ultrafast scatterings between nonequilibrium electrons and strongly coupled optical phonons, which signify the crucial role of ultrafast nonequilibrium dynamics on many-body interactions. Our results advance the understanding of many-body physics in extreme conditions, which is important for any endeavor to optically manipulate or create non-equilibrium states of matter.
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Affiliation(s)
- Marten Düvel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marco Merboldt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Jan Philipp Bange
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hannah Strauch
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Michael Stellbrink
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Klaus Pierz
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | | | - Davood Momeni
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Dino Novko
- Institute of Physics, HR-10000 Zagreb, Croatia
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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19
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Optical manipulation of Rashba-split 2-dimensional electron gas. Nat Commun 2022; 13:3096. [PMID: 35654938 PMCID: PMC9163084 DOI: 10.1038/s41467-022-30742-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 05/16/2022] [Indexed: 11/17/2022] Open
Abstract
In spintronics, the two main approaches to actively control the electrons’ spin involve static magnetic or electric fields. An alternative avenue relies on the use of optical fields to generate spin currents, which can bolster spin-device performance, allowing for faster and more efficient logic. To date, research has mainly focused on the optical injection of spin currents through the photogalvanic effect, and little is known about the direct optical control of the intrinsic spin-splitting. To explore the optical manipulation of a material’s spin properties, we consider the Rashba effect. Using time- and angle-resolved photoemission spectroscopy (TR-ARPES), we demonstrate that an optical excitation can tune the Rashba-induced spin splitting of a two-dimensional electron gas at the surface of Bi2Se3. We establish that light-induced photovoltage and charge carrier redistribution - which in concert modulate the Rashba spin-orbit coupling strength on a sub-picosecond timescale - can offer an unprecedented platform for achieving optically-driven spin logic devices. The major challenge for the development of spin based information processing is to obtain efficient ways of controlling spin. Here, Michiardi et al show that the Rashba spin-splitting at the surface of Bi2Se3 topological insulator can be controlled via optical pulses on picosecond timescales.
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20
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Wolverson D, Smith B, Da Como E, Sayers C, Wan G, Pasquali L, Cattelan M. First-Principles Estimation of Core Level Shifts for Hf, Ta, W, and Re. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:9135-9142. [PMID: 35686223 PMCID: PMC9169058 DOI: 10.1021/acs.jpcc.2c00981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/28/2022] [Indexed: 05/14/2023]
Abstract
A simple first-principles approach is used to estimate the core level shifts observed in X-ray photoelectron spectroscopy for the 4f electrons of Hf, Ta, W, and Re; these elements were selected because their 4f levels are relatively close to the Fermi energy. The approach is first tested by modeling the surface core level shifts of low-index surfaces of the four elemental metals, followed by its application to the well-studied material TaSe2 in the commensurate charge density wave (CDW) phase, where agreement with experimental data is found to be good, showing that this approach can yield insights into modifications of the CDW. Finally, unterminated surface core level shifts in the hypothetical MXene Ta3C2 are modeled, and the potential of XPS for the investigation of the surface termination of MXenes is demonstrated.
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Affiliation(s)
- Daniel Wolverson
- Centre
for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Benjamin Smith
- Centre
for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Enrico Da Como
- Centre
for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Charles Sayers
- Centre
for Nanoscience and Nanotechnology and Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Gary Wan
- Centre
for Nano Science and Quantum Information, University of Bristol, Tyndall Avenue, Bristol BS8 1FD, United Kingdom
| | - Luca Pasquali
- Department
of Engineering, University of Modena and
Reggio Emilia, Via Vivarelli
10, Modena 41125, Italy
| | - Mattia Cattelan
- School
of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, United
Kingdom
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21
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Bao J, Yang L, Wang D. Influence of torsional deformation on the electronic structure and optical properties of 1T-TaS2 monolayer. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Takubo K, Banu S, Jin S, Kaneko M, Yajima W, Kuwahara M, Hayashi Y, Ishikawa T, Okimoto Y, Hada M, Koshihara S. Generation of sub-100 fs electron pulses for time-resolved electron diffraction using a direct synchronization method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:053005. [PMID: 35649807 DOI: 10.1063/5.0086008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 05/01/2022] [Indexed: 06/15/2023]
Abstract
To investigate photoinduced phenomena in various materials and molecules, ultrashort pulsed x-ray and electron sources with high brightness and high repetition rates are required. The x-ray and electron's typical and de Broglie wavelengths are shorter than lattice constants of materials and molecules. Therefore, photoinduced structural dynamics on the femtosecond to picosecond timescales can be directly observed in a diffraction manner by using these pulses. This research created a tabletop ultrashort pulsed electron diffraction setup that used a femtosecond laser and electron pulse compression cavity that was directly synchronized to the microwave master oscillator (∼3 GHz). A compressed electron pulse with a 1 kHz repetition rate contained 228 000 electrons. The electron pulse duration was estimated to be less than 100 fs at the sample position by using photoinduced immediate lattice changes in an ultrathin silicon film (50 nm). The newly developed time-resolved electron diffraction setup has a pulse duration that is comparable to femtosecond laser pulse widths (35-100 fs). The pulse duration, in particular, fits within the timescale of photoinduced phenomena in quantum materials. Our developed ultrafast time-resolved electron diffraction setup with a sub-100 fs temporal resolution would be a powerful tool in material science with a combination of optical pump-probe, time-resolved photoemission spectroscopic, and pulsed x-ray measurements.
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Affiliation(s)
- Kou Takubo
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Samiran Banu
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Sichen Jin
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Misaki Kaneko
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Wataru Yajima
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Makoto Kuwahara
- Department of Applied Physics and Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8603, Japan
| | - Yasuhiko Hayashi
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Tadahiko Ishikawa
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Yoichi Okimoto
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Masaki Hada
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Shinya Koshihara
- Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551, Japan
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23
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Weber M, Freericks JK. Real-time evolution of static electron-phonon models in time-dependent electric fields. Phys Rev E 2022; 105:025301. [PMID: 35291073 DOI: 10.1103/physreve.105.025301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
We present an exact Monte Carlo method to simulate the nonequilibrium dynamics of electron-phonon models in the adiabatic limit of zero phonon frequency. The classical nature of the phonons allows us to sample the equilibrium phonon distribution and efficiently evolve the electronic subsystem in a time-dependent electromagnetic field for each phonon configuration. We demonstrate that our approach is particularly useful for charge-density-wave systems experiencing pulsed electric fields, as they appear in pump-probe experiments. For the half-filled Holstein model in one and two dimensions, we calculate the out-of-equilibrium response of the current and the energy after a pulse is applied as well as the photoemission spectrum before and after the pump. Finite-size effects are under control for chains of 162 sites (in one dimension) or 16×16 square lattices (in two dimensions).
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Affiliation(s)
- Manuel Weber
- Department of Physics, Georgetown University, Washington, DC 20057, USA
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany
| | - James K Freericks
- Department of Physics, Georgetown University, Washington, DC 20057, USA
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24
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Flavell W. Spiers Memorial Lecture: Prospects for photoelectron spectroscopy. Faraday Discuss 2022; 236:9-57. [DOI: 10.1039/d2fd00071g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An overview is presented of recent advances in photoelectron spectroscopy, focussing on advances in in situ and time-resolved measurements, and in extending the sampling depth of the technique. The future...
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25
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Nakata Y, Sugawara K, Chainani A, Oka H, Bao C, Zhou S, Chuang PY, Cheng CM, Kawakami T, Saruta Y, Fukumura T, Zhou S, Takahashi T, Sato T. Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe 2 and 1T-NbSe 2. Nat Commun 2021; 12:5873. [PMID: 34620875 PMCID: PMC8497551 DOI: 10.1038/s41467-021-26105-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 09/17/2021] [Indexed: 11/09/2022] Open
Abstract
Combination of low-dimensionality and electron correlation is vital for exotic quantum phenomena such as the Mott-insulating phase and high-temperature superconductivity. Transition-metal dichalcogenide (TMD) 1T-TaS2 has evoked great interest owing to its unique nonmagnetic Mott-insulator nature coupled with a charge-density-wave (CDW). To functionalize such a complex phase, it is essential to enhance the CDW-Mott transition temperature TCDW-Mott, whereas this was difficult for bulk TMDs with TCDW-Mott < 200 K. Here we report a strong-coupling 2D CDW-Mott phase with a transition temperature onset of ~530 K in monolayer 1T-TaSe2. Furthermore, the electron correlation derived lower Hubbard band survives under external perturbations such as carrier doping and photoexcitation, in contrast to the bulk counterpart. The enhanced Mott-Hubbard and CDW gaps for monolayer TaSe2 compared to NbSe2, originating in the lattice distortion assisted by strengthened correlations and disappearance of interlayer hopping, suggest stabilization of a likely nonmagnetic CDW-Mott insulator phase well above the room temperature. The present result lays the foundation for realizing monolayer CDW-Mott insulator based devices operating at room temperature.
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Affiliation(s)
- Yuki Nakata
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Katsuaki Sugawara
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Ashish Chainani
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Hirofumi Oka
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Changhua Bao
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Shaohua Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Pei-Yu Chuang
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hshinchu, 30077, Taiwan ROC
| | - Tappei Kawakami
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Yasuaki Saruta
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Tomoteru Fukumura
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Shuyun Zhou
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China
- Frontier Science Center for Quantum Information, Beijing, 100084, China
| | - Takashi Takahashi
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan
| | - Takafumi Sato
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
- Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan.
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26
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Bhowal S, Dasgupta I. Spin-orbit effects in pentavalent iridates: models and materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:453001. [PMID: 34352745 DOI: 10.1088/1361-648x/ac1aed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Spin-orbit effects in heavy 5dtransition metal oxides, in particular, iridates, have received enormous current interest due to the prediction as well as the realization of a plethora of exotic and unconventional magnetic properties. While a bulk of these works are based on tetravalent iridates (d5), where the counter-intuitive insulating state of the rather extended 5dorbitals are explained by invoking strong spin-orbit coupling, the recent quest in iridate research has shifted to the other valencies of Ir, of which pentavalent iridates constitute a notable representative. In contrast to the tetravalent iridates, spin-orbit entangled electrons ind4systems are expected to be confined to theJ= 0 singlet state without any resultant moment or magnetic response. However, it has been recently predicted that, magnetism ind4systems may occur via magnetic condensation of excitations across spin-orbit-coupled states. In reality, the magnetism in Ir5+systems are often quite debatable both from theoretical as well as experimental point of view. Here we provide a comprehensive overview of the spin-orbit coupledd4model systems and its implications in the studied pentavalent iridates. In particular, we review here the current experimental and theoretical understanding of the double perovskite (A2BYIrO6,A= Sr, Ba,B= Y, Sc, Gd), 6H-perovskite (Ba3MIr2O9,M= Zn, Mg, Sr, Ca), post-perovskite (NaIrO3), and hexagonal (Sr3MIrO6) iridates, along with a number of open questions that require future investigation.
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Affiliation(s)
- Sayantika Bhowal
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Indra Dasgupta
- School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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27
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Subpicosecond metamagnetic phase transition in FeRh driven by non-equilibrium electron dynamics. Nat Commun 2021; 12:5088. [PMID: 34429414 PMCID: PMC8384879 DOI: 10.1038/s41467-021-25347-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 07/22/2021] [Indexed: 11/11/2022] Open
Abstract
Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350 ± 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer. In FeRh, it is possible to optically drive a phase transition between ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering. Here, using a combination of photoelectron spectroscopy and ab-initio calculations, the authors demonstrate the existence of a transient intermediate phase, explaining the delayed appearance of the FM phase.
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28
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Mankowsky R, Sander M, Zerdane S, Vonka J, Bartkowiak M, Deng Y, Winkler R, Giorgianni F, Matmon G, Gerber S, Beaud P, Lemke HT. New insights into correlated materials in the time domain-combining far-infrared excitation with x-ray probes at cryogenic temperatures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:374001. [PMID: 34098537 DOI: 10.1088/1361-648x/ac08b5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Modern techniques for the investigation of correlated materials in the time domain combine selective excitation in the THz frequency range with selective probing of coupled structural, electronic and magnetic degrees of freedom using x-ray scattering techniques. Cryogenic sample temperatures are commonly required to prevent thermal occupation of the low energy modes and to access relevant material ground states. Here, we present a chamber optimized for high-field THz excitation and (resonant) x-ray diffraction at sample temperatures between 5 and 500 K. Directly connected to the beamline vacuum and featuring both a Beryllium window and an in-vacuum detector, the chamber covers the full (2-12.7) keV energy range of the femtosecond x-ray pulses available at the Bernina endstation of the SwissFEL free electron laser. Successful commissioning experiments made use of the energy tunability to selectively track the dynamics of the structural, magnetic and orbital order of Ca2RuO4and Tb2Ti2O7at the Ru (2.96 keV) and Tb (7.55 keV)L-edges, respectively. THz field amplitudes up to 1.12 MV cm-1peak field were demonstrated and used to excite the samples at temperatures as low as 5 K.
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Affiliation(s)
| | | | | | - Jakub Vonka
- Paul Scherrer Institute, Villigen, Switzerland
| | | | - Yunpei Deng
- Paul Scherrer Institute, Villigen, Switzerland
| | - Rafael Winkler
- Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | | | - Guy Matmon
- Paul Scherrer Institute, Villigen, Switzerland
| | | | - Paul Beaud
- Paul Scherrer Institute, Villigen, Switzerland
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29
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Shin D, Tancogne-Dejean N, Zhang J, Okyay MS, Rubio A, Park N. Identification of the Mott Insulating Charge Density Wave State in 1T-TaS_{2}. PHYSICAL REVIEW LETTERS 2021; 126:196406. [PMID: 34047618 DOI: 10.1103/physrevlett.126.196406] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
We investigate the low-temperature charge density wave (CDW) state of bulk TaS_{2} with a fully self-consistent density-functional theory with the Hubbard U potential, over which the controversy has remained unresolved regarding the out-of-plane metallic band. By examining the innate structure of the Hubbard U potential, we reveal that the conventional use of atomic-orbital basis could seriously misevaluate the electron correlation in the CDW state. By adopting a generalized basis, covering the whole David star, we successfully reproduce the Mott insulating nature with the layer-by-layer antiferromagnetic order. Similar consideration should be applied for description of the electron correlation in molecular solid.
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Affiliation(s)
- Dongbin Shin
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Nicolas Tancogne-Dejean
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jin Zhang
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Mahmut Sait Okyay
- Department of Physics, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Korea
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
- Nano-Bio Spectroscopy Group, Departamento de Fsica de Materiales, Universidad del Pas Vasco, 20018 San Sebastian, Spain
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - Noejung Park
- Department of Physics, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 44919, Korea
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30
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Maklar J, Windsor YW, Nicholson CW, Puppin M, Walmsley P, Esposito V, Porer M, Rittmann J, Leuenberger D, Kubli M, Savoini M, Abreu E, Johnson SL, Beaud P, Ingold G, Staub U, Fisher IR, Ernstorfer R, Wolf M, Rettig L. Nonequilibrium charge-density-wave order beyond the thermal limit. Nat Commun 2021; 12:2499. [PMID: 33941788 PMCID: PMC8093280 DOI: 10.1038/s41467-021-22778-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/26/2021] [Indexed: 12/02/2022] Open
Abstract
The interaction of many-body systems with intense light pulses may lead to novel emergent phenomena far from equilibrium. Recent discoveries, such as the optical enhancement of the critical temperature in certain superconductors and the photo-stabilization of hidden phases, have turned this field into an important research frontier. Here, we demonstrate nonthermal charge-density-wave (CDW) order at electronic temperatures far greater than the thermodynamic transition temperature. Using time- and angle-resolved photoemission spectroscopy and time-resolved X-ray diffraction, we investigate the electronic and structural order parameters of an ultrafast photoinduced CDW-to-metal transition. Tracking the dynamical CDW recovery as a function of electronic temperature reveals a behaviour markedly different from equilibrium, which we attribute to the suppression of lattice fluctuations in the transient nonthermal phonon distribution. A complete description of the system's coherent and incoherent order-parameter dynamics is given by a time-dependent Ginzburg-Landau framework, providing access to the transient potential energy surfaces.
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Affiliation(s)
- J Maklar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany.
| | - Y W Windsor
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - C W Nicholson
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
- Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Fribourg, Switzerland
| | - M Puppin
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
- Laboratory of Ultrafast Spectroscopy, ISIC, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - P Walmsley
- Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University, Stanford, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - V Esposito
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - M Porer
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - J Rittmann
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - D Leuenberger
- Department of Physics, University of Zürich, Zürich, Switzerland
| | - M Kubli
- Institute for Quantum Electronics, Physics Department, ETH Zürich, Zürich, Switzerland
| | - M Savoini
- Institute for Quantum Electronics, Physics Department, ETH Zürich, Zürich, Switzerland
| | - E Abreu
- Institute for Quantum Electronics, Physics Department, ETH Zürich, Zürich, Switzerland
| | - S L Johnson
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
- Institute for Quantum Electronics, Physics Department, ETH Zürich, Zürich, Switzerland
| | - P Beaud
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - G Ingold
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - U Staub
- Swiss Light Source, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - I R Fisher
- Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University, Stanford, CA, USA
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - R Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - M Wolf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany.
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31
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Biswas D, Jones AJH, Majchrzak P, Choi BK, Lee TH, Volckaert K, Feng J, Marković I, Andreatta F, Kang CJ, Kim HJ, Lee IH, Jozwiak C, Rotenberg E, Bostwick A, Sanders CE, Zhang Y, Karras G, Chapman RT, Wyatt AS, Springate E, Miwa JA, Hofmann P, King PDC, Chang YJ, Lanatà N, Ulstrup S. Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe 2. NANO LETTERS 2021; 21:1968-1975. [PMID: 33600187 DOI: 10.1021/acs.nanolett.0c04409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The transition-metal dichalcogenide VSe2 exhibits an increased charge density wave transition temperature and an emerging insulating phase when thinned to a single layer. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these phases in single-layer VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap, which we disentangle from the ensuing hot carrier dynamics by fitting a model spectral function to the time-dependent photoemission intensity. This procedure leads to an estimated time scale of 480 fs for the closure of the gap, which suggests that the phase transition in single-layer VSe2 is driven by electron-lattice interactions rather than by Mott-like electronic effects. The ultrafast optical switching of these interactions in SL VSe2 demonstrates the potential for controlling phase transitions in 2D materials with light.
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Affiliation(s)
- Deepnarayan Biswas
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Alfred J H Jones
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Paulina Majchrzak
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Byoung Ki Choi
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Tsung-Han Lee
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Klara Volckaert
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Jiagui Feng
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Suzhou Institute of Nano-Tech. and Nanobionics (SINANO), CAS, 398 Ruoshui Road, SEID, SIP, Suzhou 215123, China
| | - Igor Marković
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Federico Andreatta
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Chang-Jong Kang
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08856, United States
| | - Hyuk Jin Kim
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - In Hak Lee
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Charlotte E Sanders
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Yu Zhang
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Gabriel Karras
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Richard T Chapman
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Adam S Wyatt
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Emma Springate
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell 0 × 11 0QX, U.K
| | - Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Philip Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Phil D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
| | - Young Jun Chang
- Department of Physics, University of Seoul, Seoul 02504, Republic of Korea
- Department of Smart Cities, University of Seoul, Seoul, 02504, Republic of Korea
| | - Nicola Lanatà
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
- Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Søren Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
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32
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Yang LX, Rohde G, Hanff K, Stange A, Xiong R, Shi J, Bauer M, Rossnagel K. Bypassing the Structural Bottleneck in the Ultrafast Melting of Electronic Order. PHYSICAL REVIEW LETTERS 2020; 125:266402. [PMID: 33449703 DOI: 10.1103/physrevlett.125.266402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Impulsive optical excitation generally results in a complex nonequilibrium electron and lattice dynamics that involves multiple processes on distinct timescales, and a common conception is that for times shorter than about 100 fs the gap in the electronic spectrum is not seriously affected by lattice vibrations. Here, however, by directly monitoring the photoinduced collapse of the spectral gap in a canonical charge-density-wave material, the blue bronze Rb_{0.3}MoO_{3}, we find that ultrafast (∼60 fs) vibrational disordering due to efficient hot-electron energy dissipation quenches the gap significantly faster than the typical structural bottleneck time corresponding to one half-cycle oscillation (∼315 fs) of the coherent charge-density-wave amplitude mode. This result not only demonstrates the importance of incoherent lattice motion in the photoinduced quenching of electronic order, but also resolves the perennial debate about the nature of the spectral gap in a coupled electron-lattice system.
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Affiliation(s)
- L X Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - G Rohde
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Hanff
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - A Stange
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - R Xiong
- Department of Physics, Wuhan University, Wuhan 430072, People's Republic of China
| | - J Shi
- Department of Physics, Wuhan University, Wuhan 430072, People's Republic of China
| | - M Bauer
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - K Rossnagel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
- Ruprecht-Haensel-Labor, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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33
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Parameswaran SA, Gopalakrishnan S. Asymptotically Exact Theory for Nonlinear Spectroscopy of Random Quantum Magnets. PHYSICAL REVIEW LETTERS 2020; 125:237601. [PMID: 33337218 DOI: 10.1103/physrevlett.125.237601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/21/2020] [Indexed: 06/12/2023]
Abstract
We study nonlinear response in quantum spin systems near infinite-randomness critical points. Nonlinear dynamical probes, such as two-dimensional (2D) coherent spectroscopy, can diagnose the nearly localized character of excitations in such systems. We present exact results for nonlinear response in the 1D random transverse-field Ising model, from which we extract information about critical behavior that is absent in linear response. Our analysis yields exact scaling forms for the distribution functions of relaxation times that result from realistic channels for dissipation in random magnets. We argue that our results capture the scaling of relaxation times and nonlinear response in generic random quantum magnets in any spatial dimension.
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Affiliation(s)
- S A Parameswaran
- Rudolf Peierls Center for Theoretical Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - S Gopalakrishnan
- Department of Physics and Astronomy, CUNY College of Staten Island, Staten Island, New York 10314, USA
- Physics Program and Initiative for the Theoretical Sciences, The Graduate Center, CUNY, New York, New York 10016, USA
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34
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Li W, Naik GV. Large Optical Tunability from Charge Density Waves in 1T-TaS 2 under Incoherent Illumination. NANO LETTERS 2020; 20:7868-7873. [PMID: 32816498 DOI: 10.1021/acs.nanolett.0c02234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Strongly correlated materials possess a complex energy landscape and host many interesting physical phenomena, including charge density waves (CDWs). CDWs have been observed and extensively studied in many materials since their first discovery in 1972. Yet they present ample opportunities for discovery. Here, we report a large tunability in the optical response of a quasi-2D CDW material, 1T-TaS2, upon incoherent light illumination at room temperature. We hypothesize that the observed tunability is a consequence of light-induced rearrangement of CDW stacking across the layers of 1T-TaS2. Our model, based on this hypothesis, agrees reasonably well with experiments suggesting that the interdomain CDW interaction is a vital potentially knob to control the phase of strongly correlated materials.
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Affiliation(s)
- Weijian Li
- Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States
| | - Gururaj V Naik
- Electrical & Computer Engineering, Rice University, Houston, Texas 77005, United States
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35
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Dang C, Guan M, Hussain S, Wen W, Zhu Y, Jiao L, Meng S, Xie L. Phase Transition Photodetection in Charge Density Wave Tantalum Disulfide. NANO LETTERS 2020; 20:6725-6731. [PMID: 32787147 DOI: 10.1021/acs.nanolett.0c02613] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The charge density wave (CDW) phase is a macroscopic quantum state with periodic charge density modulation accompanied by periodic lattice distortion in low-dimensional metals. External fields, such as an electric field and optical excitation, can trigger the transitions among different CDW states, leaving an under-explored mechanism and attracting great interest toward optoelectronic applications. Here, we explore a photoinduced phase transition in 1T-TaS2 under an electrical field. By analyzing the phase transition probability, we obtained a linear dependence of the phase transition barrier on the electric field and laser energy density. Additionally, the threshold laser energy for the phase transition decreases linearly with an increasing applied electrical field. Finally, picojoule photodetection was realized in the visible and near-infrared ranges near the CDW transition edge. Our work will promote the understanding of the CDW phase transition mechanism as well as open pathways for optoelectronic applications.
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Affiliation(s)
- Chunhe Dang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
- Department of Chemistry, Tsinghua University, Beijing 100084, P.R. China
| | - Mengxue Guan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Sabir Hussain
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Wen Wen
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Yiming Zhu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China
| | - Liying Jiao
- Department of Chemistry, Tsinghua University, Beijing 100084, P.R. China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P.R. China
| | - Liming Xie
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P.R. China
- University of Chinese Academy of Sciences, Beijing 100049, P.R. China
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36
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Wang YD, Yao WL, Xin ZM, Han TT, Wang ZG, Chen L, Cai C, Li Y, Zhang Y. Band insulator to Mott insulator transition in 1T-TaS 2. Nat Commun 2020; 11:4215. [PMID: 32839433 PMCID: PMC7445232 DOI: 10.1038/s41467-020-18040-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/30/2020] [Indexed: 11/26/2022] Open
Abstract
1T-TaS2 undergoes successive phase transitions upon cooling and eventually enters an insulating state of mysterious origin. Some consider this state to be a band insulator with interlayer stacking order, yet others attribute it to Mott physics that support a quantum spin liquid state. Here, we determine the electronic and structural properties of 1T-TaS2 using angle-resolved photoemission spectroscopy and X-Ray diffraction. At low temperatures, the 2π/2c-periodic band dispersion, along with half-integer-indexed diffraction peaks along the c axis, unambiguously indicates that the ground state of 1T-TaS2 is a band insulator with interlayer dimerization. Upon heating, however, the system undergoes a transition into a Mott insulating state, which only exists in a narrow temperature window. Our results refute the idea of searching for quantum magnetism in 1T-TaS2 only at low temperatures, and highlight the competition between on-site Coulomb repulsion and interlayer hopping as a crucial aspect for understanding the material’s electronic properties. 1T-TaS2 possesses complex electronic phase behaviors in transition-metal di-chalcogenides, undergoing several charge-ordered phases before finally into an insulating state of unknown origin. Here, the authors determine its electronic and structural properties experimentally, revealing its origin.
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Affiliation(s)
- Y D Wang
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - W L Yao
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Z M Xin
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - T T Han
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Z G Wang
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - L Chen
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - C Cai
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China
| | - Yuan Li
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China.,Collaborative Innovation Center of Quantum Matter, 100871, Beijing, China
| | - Y Zhang
- International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing, China. .,Collaborative Innovation Center of Quantum Matter, 100871, Beijing, China.
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37
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You P, Chen D, Lian C, Zhang C, Meng S. First‐principles dynamics of photoexcited molecules and materials towards a quantum description. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2020. [DOI: 10.1002/wcms.1492] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Peiwei You
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing China
- School of Physical Sciences University of Chinese Academy of Sciences Beijing China
| | - Daqiang Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing China
- School of Physical Sciences University of Chinese Academy of Sciences Beijing China
| | - Chao Lian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing China
| | - Cui Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing China
- Songshan Lake Materials Laboratory Dongguan China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing China
- School of Physical Sciences University of Chinese Academy of Sciences Beijing China
- Songshan Lake Materials Laboratory Dongguan China
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38
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Storeck G, Horstmann JG, Diekmann T, Vogelgesang S, von Witte G, Yalunin SV, Rossnagel K, Ropers C. Structural dynamics of incommensurate charge-density waves tracked by ultrafast low-energy electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:034304. [PMID: 32596414 PMCID: PMC7311179 DOI: 10.1063/4.0000018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
We study the non-equilibrium structural dynamics of the incommensurate and nearly commensurate charge-density wave (CDW) phases in 1T-TaS 2 . Employing ultrafast low-energy electron diffraction with 1 ps temporal resolution, we investigate the ultrafast quench and recovery of the CDW-coupled periodic lattice distortion (PLD). Sequential structural relaxation processes are observed by tracking the intensities of main lattice as well as satellite diffraction peaks and the diffuse scattering background. Comparing distinct groups of diffraction peaks, we disentangle the ultrafast quench of the PLD amplitude from phonon-related reductions of the diffraction intensity. Fluence-dependent relaxation cycles reveal a long-lived partial suppression of the order parameter for up to 60 ps, far outlasting the initial amplitude recovery and electron-phonon scattering times. This delayed return to a quasi-thermal level is controlled by lattice thermalization and coincides with the population of zone-center acoustic modes, as evidenced by a structured diffuse background. The long-lived non-equilibrium order parameter suppression suggests hot populations of CDW-coupled lattice modes. Finally, a broadening of the superlattice peaks is observed at high fluences, pointing to a non-linear generation of phase fluctuations.
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Affiliation(s)
- G. Storeck
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | - J. G. Horstmann
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | - T. Diekmann
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | - S. Vogelgesang
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | - G. von Witte
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | - S. V. Yalunin
- 4th Physical Institute, Solids and Nanostructures, University of Göttingen, 37077 Göttingen, Germany
| | | | - C. Ropers
- Author to whom correspondence should be addressed:
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39
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Lee JM, Geng C, Park JW, Oshikawa M, Lee SS, Yeom HW, Cho GY. Stable Flatbands, Topology, and Superconductivity of Magic Honeycomb Networks. PHYSICAL REVIEW LETTERS 2020; 124:137002. [PMID: 32302191 DOI: 10.1103/physrevlett.124.137002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 11/08/2019] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
We propose a new principle to realize flatbands which are robust in real materials, based on a network superstructure of one-dimensional segments. This mechanism is naturally realized in the nearly commensurate charge-density wave of 1T-TaS_{2} with the honeycomb network of conducting domain walls, and the resulting flatband can naturally explain the enhanced superconductivity. We also show that corner states, which are a hallmark of the higher-order topological insulators, appear in the network superstructure.
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Affiliation(s)
- Jongjun M Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Chenhua Geng
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Jae Whan Park
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Masaki Oshikawa
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Sung-Sik Lee
- Department of Physics & Astronomy, McMaster University, 1280 Main St. W., Hamilton Ontario L85 4M1, Canada
- Perimeter Institute for Theoretical Physics, 31 Caroline ST. N., Waterloo Ontario N2L 2Y5, Canada
| | - Han Woong Yeom
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, Korea
| | - Gil Young Cho
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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40
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Coherent modulation of the electron temperature and electron-phonon couplings in a 2D material. Proc Natl Acad Sci U S A 2020; 117:8788-8793. [PMID: 32241890 DOI: 10.1073/pnas.1917341117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ultrashort light pulses can selectively excite charges, spins, and phonons in materials, providing a powerful approach for manipulating their properties. Here we use femtosecond laser pulses to coherently manipulate the electron and phonon distributions, and their couplings, in the charge-density wave (CDW) material 1T-TaSe2 After exciting the material with a femtosecond pulse, fast spatial smearing of the laser-excited electrons launches a coherent lattice breathing mode, which in turn modulates the electron temperature. This finding is in contrast to all previous observations in multiple materials to date, where the electron temperature decreases monotonically via electron-phonon scattering. By tuning the laser fluence, the magnitude of the electron temperature modulation changes from ∼200 K in the case of weak excitation, to ∼1,000 K for strong laser excitation. We also observe a phase change of π in the electron temperature modulation at a critical fluence of 0.7 mJ/cm2, which suggests a switching of the dominant coupling mechanism between the coherent phonon and electrons. Our approach opens up routes for coherently manipulating the interactions and properties of two-dimensional and other quantum materials using light.
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41
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Abstract
The role of the crystal lattice for the electronic properties of cuprates and other high-temperature superconductors remains controversial despite decades of theoretical and experimental efforts. While the paradigm of strong electronic correlations suggests a purely electronic mechanism behind the insulator-to-metal transition, recently the mutual enhancement of the electron-electron and the electron-phonon interaction and its relevance to the formation of the ordered phases have also been emphasized. Here, we combine polarization-resolved ultrafast optical spectroscopy and state-of-the-art dynamical mean-field theory to show the importance of the crystal lattice in the breakdown of the correlated insulating state in an archetypal undoped cuprate. We identify signatures of electron-phonon coupling to specific fully symmetric optical modes during the buildup of a three-dimensional (3D) metallic state that follows charge photodoping. Calculations for coherently displaced crystal structures along the relevant phonon coordinates indicate that the insulating state is remarkably unstable toward metallization despite the seemingly large charge-transfer energy scale. This hitherto unobserved insulator-to-metal transition mediated by fully symmetric lattice modes can find extensive application in a plethora of correlated solids.
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42
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Zhou L, Sun C, Li X, Tang L, Guo W, Luo L, Zhang M, Teng KS, Qian F, Lu C, Liang J, Yao Y, Lau SP. Tantalum disulfide quantum dots: preparation, structure, and properties. NANOSCALE RESEARCH LETTERS 2020; 15:20. [PMID: 31993763 PMCID: PMC6987292 DOI: 10.1186/s11671-020-3250-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
Tantalum disulfide (TaS2) two-dimensional film material has attracted wide attention due to its unique optical and electrical properties. In this work, we report the preparation of 1 T-TaS2 quantum dots (1 T-TaS2 QDs) by top-down method. Herein, we prepared the TaS2 QDs having a monodisperse grain size of around 3 nm by an effective ultrasonic liquid phase exfoliation method. Optical studies using UV-Vis, PL, and PLE techniques on the as-prepared TaS2 QDs exhibited ultraviolet absorption at 283 nm. Furthermore, we found that dimension reduction of TaS2 has led to a modification of the band gap, namely a transition from indirect to direct band gap, which is explained using first-principle calculations. By using quinine as reference, the fluorescence quantum yield is 45.6%. Therefore, our results suggest TaS2 QDs have unique and extraordinary optical properties. Moreover, the low-cost, facile method of producing high quality TaS2 QDs in this work is ideal for mass production to ensure commercial viability of devices based on this material. TaS2 quantum dots having a monodisperse grain size of around 3 nm have been prepared by an ultrasonic liquid phase exfoliation method, it has been found that the dimension reduction of TaS2 has led to a transition from indirect to direct band gap that results in the unique and extraordinary optical properties (PL QY: 45.6%).
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Affiliation(s)
- Liangliang Zhou
- Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Chuli Sun
- School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Xueming Li
- Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China.
| | - Libin Tang
- Kunming Institute of Physics, Kunming, 650223, People's Republic of China.
| | - Wei Guo
- School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
| | - Lin Luo
- Kunming Institute of Physics, Kunming, 650223, People's Republic of China
| | - Meng Zhang
- Institute of Environment and Health, Jianghan University, Wuhan, 430056, People's Republic of China
| | - Kar Seng Teng
- Teng College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK
| | - Fuli Qian
- Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Chaoyu Lu
- Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Jing Liang
- Key Laboratory of Advanced Technique & Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming, 650500, People's Republic of China
| | - Yugui Yao
- School of Physics, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Shu Ping Lau
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, SAR, People's Republic of China
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43
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Hofherr M, Häuser S, Dewhurst JK, Tengdin P, Sakshath S, Nembach HT, Weber ST, Shaw JM, Silva TJ, Kapteyn HC, Cinchetti M, Rethfeld B, Murnane MM, Steil D, Stadtmüller B, Sharma S, Aeschlimann M, Mathias S. Ultrafast optically induced spin transfer in ferromagnetic alloys. SCIENCE ADVANCES 2020; 6:eaay8717. [PMID: 32010774 PMCID: PMC6968944 DOI: 10.1126/sciadv.aay8717] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 10/09/2019] [Indexed: 05/23/2023]
Abstract
The vision of using light to manipulate electronic and spin excitations in materials on their fundamental time and length scales requires new approaches in experiment and theory to observe and understand these excitations. The ultimate speed limit for all-optical manipulation requires control schemes for which the electronic or magnetic subsystems of the materials are coherently manipulated on the time scale of the laser excitation pulse. In our work, we provide experimental evidence of such a direct, ultrafast, and coherent spin transfer between two magnetic subsystems of an alloy of Fe and Ni. Our experimental findings are fully supported by time-dependent density functional theory simulations and, hence, suggest the possibility of coherently controlling spin dynamics on subfemtosecond time scales, i.e., the birth of the research area of attomagnetism.
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Affiliation(s)
- M. Hofherr
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - S. Häuser
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - J. K. Dewhurst
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - P. Tengdin
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - S. Sakshath
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - H. T. Nembach
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - S. T. Weber
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - J. M. Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - T. J. Silva
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - H. C. Kapteyn
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - M. Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - B. Rethfeld
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - M. M. Murnane
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - D. Steil
- Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - B. Stadtmüller
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - S. Sharma
- Max Born Institute for Nonlinear Optics, Max-Born-Strasse 2A, 12489 Berlin, Germany
| | - M. Aeschlimann
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - S. Mathias
- Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Corresponding author.
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44
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Zhang J, Lian C, Guan M, Ma W, Fu H, Guo H, Meng S. Photoexcitation Induced Quantum Dynamics of Charge Density Wave and Emergence of a Collective Mode in 1 T-TaS 2. NANO LETTERS 2019; 19:6027-6034. [PMID: 31416307 DOI: 10.1021/acs.nanolett.9b01865] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photoexcitation is a powerful means in distinguishing different interactions and manipulating the states of matter, especially in charge density wave (CDW) materials. The CDW state of 1T-TaS2 has been widely studied experimentally mainly because of its intriguing laser-induced ultrafast responses of electronic and lattice subsystems. However, the microscopic atomic dynamics and underlying electronic mechanism upon photoexcitation remain unclear. Here, we demonstrate photoexcitation induced ultrafast dynamics of CDW in 1T-TaS2 using time-dependent density functional theory molecular dynamics. We discover a novel collective oscillation mode between the CDW state and a transient state induced by photodoping, which is significantly different from thermally induced phonon mode and attributed to the modification of the potential energy surface from laser excitation. In addition, our finding validates nonthermal melting of CDW induced at low light intensities, supporting that conventional hot electron model is inadequate to explain photoinduced dynamics. Our results provide a deep insight into the coherent electron and lattice quantum dynamics during the formation and excitation of CDW in 1T-TaS2.
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Affiliation(s)
- Jin Zhang
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Chao Lian
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
| | - Mengxue Guan
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Wei Ma
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Huixia Fu
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Haizhong Guo
- School of Physics and Engineering , Zhengzhou University , Zhengzhou , Henan 450001 , P. R. China
| | - Sheng Meng
- Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
- Songshan Lake Materials Laboratory , Dongguan , Guangdong 523808 , P. R. China
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45
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Gauzzi A, Moutaabbid H, Klein Y, Loupias G, Hardy V. Fermi- to non-Fermi-liquid crossover and Kondo behavior in two-dimensional (Cu 2/3V 1/3)V 2S 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:31LT01. [PMID: 31035261 DOI: 10.1088/1361-648x/ab1d9b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
By means of a specific heat (C) and electrical resistivity ([Formula: see text]) study, we give evidence of a pronounced Fermi liquid (FL) behavior with sizable mass renormalization, [Formula: see text], up to unusually high temperatures ∼70 K in the layered system (Cu2/3V1/3)V2S4. At low temperature, a marked upturn of both C and [Formula: see text] is suppressed by magnetic field, which suggests a picture of Kondo coupling between conduction electrons in the VS2 layers and impurity spins of the V3+ ions located between layers. This picture opens the possibility of controlling electronic correlations and the FL to non-FL crossover in simple layered materials. For instance, we envisage that the coupling between layers provided by the impurity spins may realize a two-channel Kondo state.
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Affiliation(s)
- A Gauzzi
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC) UMR7590, Sorbonne Université/CNRS/Museum National d'Histoire Naturelle, 4 place Jussieu, 75005 Paris, France
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46
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Sie EJ, Rohwer T, Lee C, Gedik N. Time-resolved XUV ARPES with tunable 24-33 eV laser pulses at 30 meV resolution. Nat Commun 2019; 10:3535. [PMID: 31388015 PMCID: PMC6684652 DOI: 10.1038/s41467-019-11492-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 07/15/2019] [Indexed: 11/09/2022] Open
Abstract
High harmonic generation of ultrafast laser pulses can be used to perform angle-resolved photoemission spectroscopy (ARPES) to map the electronic band structure of materials with femtosecond time resolution. However, currently it is difficult to reach high momenta with narrow energy resolution. Here, we combine a gas phase extreme ultraviolet (XUV) femtosecond light source, an XUV monochromator, and a time-of-flight electron analyzer to develop XUV-based time-resolved ARPES. Our technique can produce tunable photon energy between 24-33 eV with an unprecedented energy resolution of 30 meV and time resolution of 200 fs. This technique enables time-, energy- and momentum-resolved investigation of the nonequilibrium dynamics of electrons in materials with a full access to their first Brillouin zone. We evaluate the performance of this setup through exemplary measurements on various quantum materials, including WTe2, WSe2, TiSe2, and Bi2Sr2CaCu2O8+δ.
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Affiliation(s)
- Edbert J Sie
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Timm Rohwer
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Changmin Lee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Nuh Gedik
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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47
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Mills AK, Zhdanovich S, Na MX, Boschini F, Razzoli E, Michiardi M, Sheyerman A, Schneider M, Hammond TJ, Süss V, Felser C, Damascelli A, Jones DJ. Cavity-enhanced high harmonic generation for extreme ultraviolet time- and angle-resolved photoemission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:083001. [PMID: 31472611 DOI: 10.1063/1.5090507] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/14/2019] [Indexed: 06/10/2023]
Abstract
With its direct correspondence to electronic structure, angle-resolved photoemission spectroscopy (ARPES) is a ubiquitous tool for the study of solids. When extended to the temporal domain, time-resolved (TR)-ARPES offers the potential to move beyond equilibrium properties, exploring both the unoccupied electronic structure as well as its dynamical response under ultrafast perturbation. Historically, ultrafast extreme ultraviolet sources employing high-order harmonic generation (HHG) have required compromises that make it challenging to achieve a high energy resolution-which is highly desirable for many TR-ARPES studies-while producing high photon energies and a high photon flux. We address this challenge by performing HHG inside a femtosecond enhancement cavity, realizing a practical source for TR-ARPES that achieves a flux of over 1011 photons/s delivered to the sample, operates over a range of 8-40 eV with a repetition rate of 60 MHz. This source enables TR-ARPES studies with a temporal and energy resolution of 190 fs and 22 meV, respectively. To characterize the system, we perform ARPES measurements of polycrystalline Au and MoTe2, as well as TR-ARPES studies on graphite.
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Affiliation(s)
- A K Mills
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - S Zhdanovich
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M X Na
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - F Boschini
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - E Razzoli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Michiardi
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - A Sheyerman
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - M Schneider
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - T J Hammond
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - V Süss
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - C Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - A Damascelli
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - D J Jones
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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48
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Chávez-Cervantes M, Topp GE, Aeschlimann S, Krause R, Sato SA, Sentef MA, Gierz I. Charge Density Wave Melting in One-Dimensional Wires with Femtosecond Subgap Excitation. PHYSICAL REVIEW LETTERS 2019; 123:036405. [PMID: 31386485 DOI: 10.1103/physrevlett.123.036405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 05/16/2019] [Indexed: 06/10/2023]
Abstract
Charge density waves (CDWs) are symmetry-broken ground states that commonly occur in low-dimensional metals due to strong electron-electron and/or electron-phonon coupling. The nonequilibrium carrier distribution established via photodoping with femtosecond laser pulses readily quenches these ground states and induces an ultrafast insulator-to-metal phase transition. To date, CDW melting has been mainly investigated in the single-photon regime with pump photon energies bigger than the gap size. The recent development of strong-field midinfrared sources now enables the investigation of CDW dynamics following subgap excitation. Here we excite prototypical one-dimensional indium wires with a CDW gap of ∼300 meV with midinfrared pulses at ℏω=190 meV with MV/cm field strength and probe the transient electronic structure with time- and angle-resolved photoemission spectroscopy. We find that the CDW gap is filled on a timescale short compared to our temporal resolution of 300 fs and that the band structure changes are completed within ∼1 ps. Supported by a minimal theoretical model we attribute our findings to multiphoton absorption across the CDW gap.
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Affiliation(s)
- M Chávez-Cervantes
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - G E Topp
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - S Aeschlimann
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - R Krause
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - S A Sato
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - M A Sentef
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - I Gierz
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Hamburg 22761, Germany
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49
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Matveev OP, Shvaika AM, Devereaux TP, Freericks JK. Stroboscopic Tests for Thermalization of Electrons in Pump-Probe Experiments. PHYSICAL REVIEW LETTERS 2019; 122:247402. [PMID: 31322387 DOI: 10.1103/physrevlett.122.247402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 05/20/2019] [Indexed: 06/10/2023]
Abstract
One of the goals of pump-probe spectroscopies is to determine how electrons relax after they have been driven out of equilibrium. It is challenging to determine how close electrons are to a thermal state solely by fitting their distribution to a Fermi-Dirac distribution. Instead, we propose that one compare the effective temperatures of both fermions and collective bosonic modes (derived from the fermions) to determine the distance from a thermal state. Measurements of effective fermionic and bosonic temperatures can be achieved directly via photoemission and nonresonant Raman scattering. Their difference quantifies the distance from thermal equilibrium.
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Affiliation(s)
- O P Matveev
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Lviv, 79011 Ukraine
- Department of Physics, Georgetown University, Washington, DC 20057, USA
| | - A M Shvaika
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Lviv, 79011 Ukraine
| | - T P Devereaux
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J K Freericks
- Department of Physics, Georgetown University, Washington, DC 20057, USA
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50
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Uhrig GS, Kalthoff MH, Freericks JK. Positivity of the Spectral Densities of Retarded Floquet Green Functions. PHYSICAL REVIEW LETTERS 2019; 122:130604. [PMID: 31012632 DOI: 10.1103/physrevlett.122.130604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 06/09/2023]
Abstract
Periodically driven nonequilibrium many-body systems are interesting because they have quasi-energy spectra, which can be tailored by controlling the external driving fields. We derive the general spectral representation of retarded Green functions in the Floquet regime, thereby generalizing the well-known Lehmann representation from equilibrium many-body physics. The derived spectral Floquet representation allows us to prove the non-negativity of spectral densities and to determine exact spectral sum rules, which can be employed to benchmark the accuracy of approximations to the exact Floquet many-body Green functions.
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Affiliation(s)
- Götz S Uhrig
- Lehrstuhl für Theoretische Physik I, Technische Universität Dortmund, Otto-Hahn Straße 4, 44221 Dortmund, Germany
| | - Mona H Kalthoff
- Lehrstuhl für Theoretische Physik I, Technische Universität Dortmund, Otto-Hahn Straße 4, 44221 Dortmund, Germany
| | - James K Freericks
- Department of Physics, Georgetown University, 37th St. and O St., NW, Washington, DC 20057, USA
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