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Moradifar P, Liu Y, Shi J, Siukola Thurston ML, Utzat H, van Driel TB, Lindenberg AM, Dionne JA. Accelerating Quantum Materials Development with Advances in Transmission Electron Microscopy. Chem Rev 2023. [PMID: 37979189 DOI: 10.1021/acs.chemrev.2c00917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2023]
Abstract
Quantum materials are driving a technology revolution in sensing, communication, and computing, while simultaneously testing many core theories of the past century. Materials such as topological insulators, complex oxides, superconductors, quantum dots, color center-hosting semiconductors, and other types of strongly correlated materials can exhibit exotic properties such as edge conductivity, multiferroicity, magnetoresistance, superconductivity, single photon emission, and optical-spin locking. These emergent properties arise and depend strongly on the material's detailed atomic-scale structure, including atomic defects, dopants, and lattice stacking. In this review, we describe how progress in the field of electron microscopy (EM), including in situ and in operando EM, can accelerate advances in quantum materials and quantum excitations. We begin by describing fundamental EM principles and operation modes. We then discuss various EM methods such as (i) EM spectroscopies, including electron energy loss spectroscopy (EELS), cathodoluminescence (CL), and electron energy gain spectroscopy (EEGS); (ii) four-dimensional scanning transmission electron microscopy (4D-STEM); (iii) dynamic and ultrafast EM (UEM); (iv) complementary ultrafast spectroscopies (UED, XFEL); and (v) atomic electron tomography (AET). We describe how these methods could inform structure-function relations in quantum materials down to the picometer scale and femtosecond time resolution, and how they enable precision positioning of atomic defects and high-resolution manipulation of quantum materials. For each method, we also describe existing limitations to solve open quantum mechanical questions, and how they might be addressed to accelerate progress. Among numerous notable results, our review highlights how EM is enabling identification of the 3D structure of quantum defects; measuring reversible and metastable dynamics of quantum excitations; mapping exciton states and single photon emission; measuring nanoscale thermal transport and coupled excitation dynamics; and measuring the internal electric field and charge density distribution of quantum heterointerfaces- all at the quantum materials' intrinsic atomic and near atomic-length scale. We conclude by describing open challenges for the future, including achieving stable sample holders for ultralow temperature (below 10K) atomic-scale spatial resolution, stable spectrometers that enable meV energy resolution, and high-resolution, dynamic mapping of magnetic and spin fields. With atomic manipulation and ultrafast characterization enabled by EM, quantum materials will be poised to integrate into many of the sustainable and energy-efficient technologies needed for the 21st century.
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Affiliation(s)
- Parivash Moradifar
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Yin Liu
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jiaojian Shi
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | | | - Hendrik Utzat
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aaron M Lindenberg
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | - Jennifer A Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
- Department of Radiology, Stanford University, Stanford, California 94305, United States
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2
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Guo Y, Qiu D, Shao M, Song J, Wang Y, Xu M, Yang C, Li P, Liu H, Xiong J. Modulations in Superconductors: Probes of Underlying Physics. Adv Mater 2023; 35:e2209457. [PMID: 36504310 DOI: 10.1002/adma.202209457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/16/2022] [Indexed: 06/02/2023]
Abstract
The importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of competing phases, electronic correlation, and phase coherence essential to global superconductivity. Here, for a comprehensive review, these techniques together with the established modulation methods, such as elemental substitution, annealing, and polarization-induced gating, are contextualized. Depending on the mechanism of each method, the modulations are categorized into stoichiometric manipulation, electrostatic gating, mechanical modulation, and geometrical design. Their recent advances are highlighted by applications in newly discovered superconductors, e.g., nickelates, Kagome metals, and magic-angle graphene. Overall, the review is to provide systematic modulations in emergent superconductors and serve as the coordinate for future investigations, which can stimulate researchers in superconductivity and other fields to perform various modulations toward a thorough understanding of quantum materials.
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Affiliation(s)
- Yehao Guo
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Mingxin Shao
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jingyan Song
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Yang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Minyi Xu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chao Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Haiwen Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
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Nicoletti D, Buzzi M, Fechner M, Dolgirev PE, Michael MH, Curtis JB, Demler E, Gu GD, Cavalleri A. Coherent emission from surface Josephson plasmons in striped cuprates. Proc Natl Acad Sci U S A 2022; 119:e2211670119. [PMID: 36126100 DOI: 10.1073/pnas.2211670119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We observe anomalous terahertz emission in photo-excited high-TC cuprates with coexisting superconductivity and charge-stripe order, in absence of any external magnetic field or current bias. Because this phenomenon should be forbidden by symmetry, our observation indicates a symmetry breaking in the stripe phase. The emission spectrum reveals the excitation of surface Josephson plasmons, which are generally dark modes but become coupled to the electromagnetic continuum in these materials by the presence of stripes. The study of coherent anomalous terahertz emission emerges as a sensitive tool to probe the symmetry of superconductors in the presence of frustrated couplings, which is a key topic in the physics of these materials. The interplay between charge order and superconductivity remains one of the central themes of research in quantum materials. In the case of cuprates, the coupling between striped charge fluctuations and local electromagnetic fields is especially important, as it affects transport properties, coherence, and dimensionality of superconducting correlations. Here, we study the emission of coherent terahertz radiation in single-layer cuprates of the La2-xBaxCuO4 family, for which this effect is expected to be forbidden by symmetry. We find that emission vanishes for compounds in which the stripes are quasi-static but is activated when c-axis inversion symmetry is broken by incommensurate or fluctuating charge stripes, such as in La1.905Ba0.095CuO4 and in La1.845Ba0.155CuO4. In this case, terahertz radiation is emitted by surface Josephson plasmons, which are generally dark modes, but couple to free space electromagnetic radiation because of the stripe modulation.
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Tidey JP, Liu EP, Lai YC, Chuang YC, Chen WT, Cane LJ, Lester C, Petsch AND, Herlihy A, Simonov A, Hayden SM, Senn M. Pronounced interplay between intrinsic phase-coexistence and octahedral tilt magnitude in hole-doped lanthanum cuprates. Sci Rep 2022; 12:14343. [PMID: 35995852 DOI: 10.1038/s41598-022-18574-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 08/16/2022] [Indexed: 11/29/2022] Open
Abstract
Definitive understanding of superconductivity and its interplay with structural symmetry in the hole-doped lanthanum cuprates remains elusive. The suppression of superconductivity around 1/8th doping maintains particular focus, often attributed to charge-density waves (CDWs) ordering in the low-temperature tetragonal (LTT) phase. Central to many investigations into this interplay is the thesis that La1.875Ba0.125CuO4 and particularly La1.675Eu0.2Sr0.125CuO4 present model systems of purely LTT structure at low temperature. However, combining single-crystal and high-resolution powder X-ray diffraction, we find these to exhibit significant, intrinsic coexistence of LTT and low-temperature orthorhombic domains, typically associated with superconductivity, even at 10 K. Our two-phase models reveal substantially greater tilting of CuO6 octahedra in the LTT phase, markedly buckling the CuO2 planes. This would couple significantly to band narrowing, potentially indicating a picture of electronically driven phase segregation, reminiscent of optimally doped manganites. These results call for reassessment of many experiments seeking to elucidate structural and electronic interplay at 1/8 doping.
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Dong T, Zhang SJ, Wang NL. Recent Development of Ultrafast Optical Characterizations for Quantum Materials. Adv Mater 2022:e2110068. [PMID: 35853841 DOI: 10.1002/adma.202110068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Kumar G, Chung PW. Selective Phonon Stimulation Mechanism to Tune Thermal Transport. ACS Omega 2022; 7:12787-12794. [PMID: 35474781 PMCID: PMC9026079 DOI: 10.1021/acsomega.1c07364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
In this paper, we determine the degree to which changes can be induced in the equilibrium thermal diffusivity and conductivity of a material via a selective nonequilibrium infrared stimulation mechanism for phonons. Using the molecular crystal RDX, we use detailed momentum-dependent coupling information across the entire Brillouin zone and the phonon gas model to show that stimulating selected modes in the spectrum of a target material can induce substantial changes in the overall thermal transport properties. Specifically in the case of RDX, stimulating modes at ∼22.74 cm-1 over a linewidth of 1 cm-1 can lead to enhanced scattering rates that reduce the overall thermal diffusivity and conductivity by 15.58 and 12.46%, respectively, from their equilibrium values. Due to the rich spectral content in the materials, however, stimulating modes near ∼1140.67 cm-1 over a similar bandwidth can produce an increase in the thermal diffusivity and conductivity by 55.73 and 144.07%, respectively. The large changes suggest a mechanism to evoke substantially modulated thermal transport properties through light-matter interaction.
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Buzzi M, Nicoletti D, Fava S, Jotzu G, Miyagawa K, Kanoda K, Henderson A, Siegrist T, Schlueter JA, Nam MS, Ardavan A, Cavalleri A. Phase Diagram for Light-Induced Superconductivity in κ-(ET)_{2}-X. Phys Rev Lett 2021; 127:197002. [PMID: 34797153 DOI: 10.1103/physrevlett.127.197002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
Resonant optical excitation of certain molecular vibrations in κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Br has been shown to induce transient superconductinglike optical properties at temperatures far above equilibrium T_{c}. Here, we report experiments across the bandwidth-tuned phase diagram of this class of materials, and study the Mott insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl and the metallic compound κ-(BEDT-TTF)_{2}Cu(NCS)_{2}. We find nonequilibrium photoinduced superconductivity only in κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Br, indicating that the proximity to the Mott insulating phase and possibly the presence of preexisting superconducting fluctuations are prerequisites for this effect.
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Affiliation(s)
- M Buzzi
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - D Nicoletti
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - S Fava
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - G Jotzu
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - K Miyagawa
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - K Kanoda
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - A Henderson
- National High Magnetic Field Laboratory, 1800 E Paul Dirac Drive, Tallahassee, Florida 31310, USA
| | - T Siegrist
- National High Magnetic Field Laboratory, 1800 E Paul Dirac Drive, Tallahassee, Florida 31310, USA
| | - J A Schlueter
- National High Magnetic Field Laboratory, 1800 E Paul Dirac Drive, Tallahassee, Florida 31310, USA
- Division of Material Research, National Science Foundation, Alexandria, Virginia 22314, USA
| | - M-S Nam
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A Ardavan
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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8
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Afanasiev D, Hortensius JR, Ivanov BA, Sasani A, Bousquet E, Blanter YM, Mikhaylovskiy RV, Kimel AV, Caviglia AD. Ultrafast control of magnetic interactions via light-driven phonons. Nat Mater 2021; 20:607-611. [PMID: 33558717 PMCID: PMC7610706 DOI: 10.1038/s41563-021-00922-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 01/07/2021] [Indexed: 05/06/2023]
Abstract
Resonant ultrafast excitation of infrared-active phonons is a powerful technique with which to control the electronic properties of materials that leads to remarkable phenomena such as the light-induced enhancement of superconductivity1,2, switching of ferroelectric polarization3,4 and ultrafast insulator-to-metal transitions5. Here, we show that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses tuned to resonance with a phonon mode of the archetypical antiferromagnet DyFeO3 induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. Non-thermal lattice control of the magnetic exchange, which defines the stability of the macroscopic magnetic state, allows us to perform picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders. Our discovery emphasizes the potential of resonant phonon excitation for the manipulation of ferroic order on ultrafast timescales6.
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Affiliation(s)
- D Afanasiev
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
| | - J R Hortensius
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - B A Ivanov
- Institute of Magnetism, National Academy of Sciences and Ministry of Education and Science, Kiev, Ukraine
- National University of Science and Technology MISiS, Moscow, Russian Federation
| | - A Sasani
- CESAM QMAT Physique Théorique des Matériaux, Université de Liège, Liège, Belgium
| | - E Bousquet
- CESAM QMAT Physique Théorique des Matériaux, Université de Liège, Liège, Belgium
| | - Y M Blanter
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | | | - A V Kimel
- Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, the Netherlands
| | - A D Caviglia
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
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Isgandarov E, Ropagnol X, Singh M, Ozaki T. Intense terahertz generation from photoconductive antennas. Front Optoelectron 2021; 14:64-93. [PMID: 36637784 PMCID: PMC9743868 DOI: 10.1007/s12200-020-1081-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/16/2020] [Indexed: 06/14/2023]
Abstract
In this paper, we review the past and recent works on generating intense terahertz (THz) pulses from photoconductive antennas (PCAs). We will focus on two types of large-aperture photoconductive antenna (LAPCA) that can generate high-intensity THz pulses (a) those with large-aperture dipoles and (b) those with interdigitated electrodes. We will first describe the principles of THz generation from PCAs. The critical parameters for improving the peak intensity of THz radiation from LAPCAs are summarized. We will then describe the saturation and limitation process of LAPCAs along with the advantages and disadvantages of working with wide-bandgap semiconductor substrates. Then, we will explain the evolution of LAPCA with interdigitated electrodes, which allows one to reduce the photoconductive gap size, and thus obtain higher bias fields while applying lower voltages. We will also describe recent achievements in intense THz pulses generated by interdigitated LAPCAs based on wide-bandgap semiconductors driven by amplified lasers. Finally, we will discuss the future perspectives of THz pulse generation using LAPCAs.
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Affiliation(s)
- Elchin Isgandarov
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
| | - Xavier Ropagnol
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
- Département de Génie Électrique, École de Technologie Supérieure (ETS), Montréal, Québec, H3C 1K3, Canada
| | - Mangaljit Singh
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada
| | - Tsuneyuki Ozaki
- Institut National de la Recherche Scientifique, Centre Énergie, Matériaux Télécommunications (INRS-EMT), Varennes, Québec, J3X 1S2, Canada.
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Jang H, Kim HD, Kim M, Park SH, Kwon S, Lee JY, Park SY, Park G, Kim S, Hyun H, Hwang S, Lee CS, Lim CY, Gang W, Kim M, Heo S, Kim J, Jung G, Kim S, Park J, Kim J, Shin H, Park J, Koo TY, Shin HJ, Heo H, Kim C, Min CK, Han JH, Kang HS, Lee HS, Kim KS, Eom I, Rah S. Time-resolved resonant elastic soft x-ray scattering at Pohang Accelerator Laboratory X-ray Free Electron Laser. Rev Sci Instrum 2020; 91:083904. [PMID: 32872965 DOI: 10.1063/5.0016414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Resonant elastic x-ray scattering has been widely employed for exploring complex electronic ordering phenomena, such as charge, spin, and orbital order, in particular, in strongly correlated electronic systems. In addition, recent developments in pump-probe x-ray scattering allow us to expand the investigation of the temporal dynamics of such orders. Here, we introduce a new time-resolved Resonant Soft X-ray Scattering (tr-RSXS) endstation developed at the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). This endstation has an optical laser (wavelength of 800 nm plus harmonics) as the pump source. Based on the commissioning results, the tr-RSXS at PAL-XFEL can deliver a soft x-ray probe (400 eV-1300 eV) with a time resolution of ∼100 fs without jitter correction. As an example, the temporal dynamics of a charge density wave on a high-temperature cuprate superconductor is demonstrated.
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Affiliation(s)
- Hoyoung Jang
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Hyeong-Do Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Minseok Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Sang Han Park
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Soonnam Kwon
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Ju Yeop Lee
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Sang-Youn Park
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Gisu Park
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Seonghan Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - HyoJung Hyun
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Sunmin Hwang
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Chae-Soon Lee
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Chae-Yong Lim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Wonup Gang
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Myeongjin Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Seongbeom Heo
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Jinhong Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Gigun Jung
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Seungnam Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Jaeku Park
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Jihwa Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Hocheol Shin
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Jaehun Park
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Tae-Yeong Koo
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Hyun-Joon Shin
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Hoon Heo
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Changbum Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Changi-Ki Min
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Jang-Hui Han
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Heung-Sik Kang
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Heung-Soo Lee
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Kyung Sook Kim
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Intae Eom
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
| | - Seungyu Rah
- PAL-XFEL, Pohang Accelerator Laboratory, Pohang, Gyeongbuk 37673, South Korea
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11
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Gao H, Schlawin F, Buzzi M, Cavalleri A, Jaksch D. Photoinduced Electron Pairing in a Driven Cavity. Phys Rev Lett 2020; 125:053602. [PMID: 32794849 DOI: 10.1103/physrevlett.125.053602] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate how virtual scattering of laser photons inside a cavity via two-photon processes can induce controllable long-range electron interactions in two-dimensional materials. We show that laser light that is red (blue) detuned from the cavity yields attractive (repulsive) interactions whose strength is proportional to the laser intensity. Furthermore, we find that the interactions are not screened effectively except at very low frequencies. For realistic cavity parameters, laser-induced heating of the electrons by inelastic photon scattering is suppressed and coherent electron interactions dominate. When the interactions are attractive, they cause an instability in the Cooper channel at a temperature proportional to the square root of the driving intensity. Our results provide a novel route for engineering electron interactions in a wide range of two-dimensional materials including AB-stacked bilayer graphene and the conducting interface between LaAlO_{3} and SrTiO_{3}.
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Affiliation(s)
- Hongmin Gao
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Frank Schlawin
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Michele Buzzi
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Andrea Cavalleri
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Dieter Jaksch
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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12
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Frano A, Blanco-Canosa S, Keimer B, Birgeneau RJ. Charge ordering in superconducting copper oxides. J Phys Condens Matter 2020; 32:374005. [PMID: 31829986 DOI: 10.1088/1361-648x/ab6140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 12/12/2019] [Indexed: 06/10/2023]
Abstract
Charge order has recently been identified as a leading competitor of high-temperature superconductivity in moderately doped cuprates. We provide a survey of universal and materials-specific aspects of this phenomenon, with emphasis on results obtained by scattering methods. In particular, we discuss the structure, periodicity, and stability range of the charge-ordered state, its response to various external perturbations, the influence of disorder, the coexistence and competition with superconductivity, as well as collective charge dynamics. In the context of this journal issue which honors Roger Cowley's legacy, we also discuss the connection of charge ordering with lattice vibrations and the central-peak phenomenon. We end the review with an outlook on research opportunities offered by new synthesis methods and experimental platforms, including cuprate thin films and superlattices.
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Affiliation(s)
- Alex Frano
- Department of Physics, University of California, San Diego, CA 92093, United States of America
| | - Santiago Blanco-Canosa
- Donostia International Physics Center, DIPC, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Basque Country, Spain
| | - Bernhard Keimer
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Robert J Birgeneau
- Department of Physics, University of California, Berkeley, CA 94720, United States of America
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720, United States of America
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13
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Mitrano M, Lee S, Husain AA, Delacretaz L, Zhu M, de la Peña Munoz G, Sun SXL, Joe YI, Reid AH, Wandel SF, Coslovich G, Schlotter W, van Driel T, Schneeloch J, Gu GD, Hartnoll S, Goldenfeld N, Abbamonte P. Ultrafast time-resolved x-ray scattering reveals diffusive charge order dynamics in La 2-x Ba x CuO 4. Sci Adv 2019; 5:eaax3346. [PMID: 31453340 PMCID: PMC6697434 DOI: 10.1126/sciadv.aax3346] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/03/2019] [Indexed: 05/23/2023]
Abstract
Charge order is universal among high-T c cuprates, but its relation to superconductivity is unclear. While static order competes with superconductivity, dynamic order may be favorable and even contribute to Cooper pairing. Using time-resolved resonant soft x-ray scattering at a free-electron laser, we show that the charge order in prototypical La2-x Ba x CuO4 exhibits transverse fluctuations at picosecond time scales. These sub-millielectron volt excitations propagate by Brownian-like diffusion and have an energy scale remarkably close to the superconducting T c. At sub-millielectron volt energy scales, the dynamics are governed by universal scaling laws defined by the propagation of topological defects. Our results show that charge order in La2-x Ba x CuO4 exhibits dynamics favorable to the in-plane superconducting tunneling and establish time-resolved x-rays as a means to study excitations at energy scales inaccessible to conventional scattering techniques.
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Affiliation(s)
- Matteo Mitrano
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Sangjun Lee
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ali A. Husain
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Luca Delacretaz
- Department of Physics, Stanford University, Stanford, CA 94305-4060, USA
| | - Minhui Zhu
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | - Stella X.-L. Sun
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Young Il Joe
- National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Alexander H. Reid
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Scott F. Wandel
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Giacomo Coslovich
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - William Schlotter
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Tim van Driel
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - John Schneeloch
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - G. D. Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Sean Hartnoll
- Department of Physics, Stanford University, Stanford, CA 94305-4060, USA
| | - Nigel Goldenfeld
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Peter Abbamonte
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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14
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Buzzi M, Först M, Cavalleri A. Measuring non-equilibrium dynamics in complex solids with ultrashort X-ray pulses. Philos Trans A Math Phys Eng Sci 2019; 377:20170478. [PMID: 30929635 PMCID: PMC6452049 DOI: 10.1098/rsta.2017.0478] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Strong interactions between electrons give rise to the complexity of quantum materials, which exhibit exotic functional properties and extreme susceptibility to external perturbations. A growing research trend involves the study of these materials away from equilibrium, especially in cases in which the stimulation with optical pulses can coherently enhance cooperative orders. Time-resolved X-ray probes are integral to this type of research, as they can be used to track atomic and electronic structures as they evolve on ultrafast timescales. Here, we review a series of recent experiments where femtosecond X-ray diffraction was used to measure dynamics of complex solids. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.
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Affiliation(s)
- Michele Buzzi
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - Michael Först
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
| | - Andrea Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
- Department of Physics, Oxford University, Clarendon Laboratory, Oxford, UK
- e-mail:
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15
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Nicoletti D, Fu D, Mehio O, Moore S, Disa AS, Gu GD, Cavalleri A. Magnetic-Field Tuning of Light-Induced Superconductivity in Striped La_{2-x}Ba_{x}CuO_{4}. Phys Rev Lett 2018; 121:267003. [PMID: 30636150 DOI: 10.1103/physrevlett.121.267003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Indexed: 06/09/2023]
Abstract
Optical excitation of stripe-ordered La_{2-x}Ba_{x}CuO_{4} has been shown to transiently enhance superconducting tunneling between the CuO_{2} planes. This effect was revealed by a blueshift, or by the appearance of a Josephson plasma resonance in the terahertz-frequency optical properties. Here, we show that this photoinduced state can be strengthened by the application of high external magnetic fields oriented along the c axis. For a 7 T field, we observe up to a tenfold enhancement in the transient interlayer phase correlation length, accompanied by a twofold increase in the relaxation time of the photoinduced state. These observations are highly surprising, since static magnetic fields suppress interlayer Josephson tunneling and stabilize stripe order at equilibrium. We interpret our data as an indication that optically enhanced interlayer coupling in La_{2-x}Ba_{x}CuO_{4} does not originate from a simple optical melting of stripes, as previously hypothesized. Rather, we speculate that the photoinduced state may emerge from activated tunneling between optically excited stripes in adjacent planes.
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Affiliation(s)
- D Nicoletti
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - D Fu
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - O Mehio
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - S Moore
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - A S Disa
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - G D Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - A Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
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16
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Abstract
Diffraction imaging of nonequilibrium dynamics at atomic resolution is becoming possible with X-ray free-electron lasers. However, there are unresolved problems with applying this method to objects that are confined in only one dimension. Here I show that reliable one-dimensional coherent diffraction imaging is possible by splicing together images recovered from different time delays in an optical pump X-ray probe experiment. The time and space evolution of antiferromagnetic order in a vibrationally excited complex oxide heterostructure is recovered from time-resolved measurements of a resonant soft X-ray diffraction peak. Midinfrared excitation of the substrate is shown to lead to a demagnetization front that propagates at a velocity exceeding the speed of sound, a critical observation for the understanding of driven phase transitions in complex condensed matter.
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Affiliation(s)
- Kenneth R Beyerlein
- Condensed Matter Dynamics Department, Max Plank Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany;
- Center for Free-Electron Laser Science, 22761 Hamburg, Germany
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17
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Abstract
The effect of electron-phonon coupling in materials can be interpreted as a dressing of the electronic structure by the lattice vibration, leading to vibrational replicas and hybridization of electronic states. In solids, a resonantly excited coherent phonon leads to a periodic oscillation of the atomic lattice in a crystal structure bringing the material into a nonequilibrium electronic configuration. Periodically oscillating quantum systems can be understood in terms of Floquet theory, which has a long tradition in the study of semiclassical light-matter interaction. Here, we show that the concepts of Floquet analysis can be applied to coherent lattice vibrations. This coupling leads to phonon-dressed quasi-particles imprinting specific signatures in the spectrum of the electronic structure. Such dressed electronic states can be detected by time- and angular-resolved photoelectron spectroscopy (ARPES) manifesting as sidebands to the equilibrium band structure. Taking graphene as a paradigmatic material with strong electron-phonon interaction and nontrivial topology, we show how the phonon-dressed states display an intricate sideband structure revealing the electron-phonon coupling at the Brillouin zone center and topological ordering of the Dirac bands. We demonstrate that if time-reversal symmetry is broken by the coherent lattice perturbations a topological phase transition can be induced. This work establishes that the recently demonstrated concept of light-induced nonequilibrium Floquet phases can also be applied when using coherent phonon modes for the dynamical control of material properties.
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Affiliation(s)
- Hannes Hübener
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Center for Free-Electron Laser Science and Department of Physics, University of Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Umberto De Giovannini
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Center for Free-Electron Laser Science and Department of Physics, University of Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Center for Free-Electron Laser Science and Department of Physics, University of Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute , 162 Fifth Avenue, New York, New York 22761, USA
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18
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Abela R, Beaud P, van Bokhoven JA, Chergui M, Feurer T, Haase J, Ingold G, Johnson SL, Knopp G, Lemke H, Milne CJ, Pedrini B, Radi P, Schertler G, Standfuss J, Staub U, Patthey L. Perspective: Opportunities for ultrafast science at SwissFEL. Struct Dyn 2017; 4:061602. [PMID: 29376109 PMCID: PMC5758366 DOI: 10.1063/1.4997222] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 10/17/2017] [Indexed: 05/03/2023]
Abstract
We present the main specifications of the newly constructed Swiss Free Electron Laser, SwissFEL, and explore its potential impact on ultrafast science. In light of recent achievements at current X-ray free electron lasers, we discuss the potential territory for new scientific breakthroughs offered by SwissFEL in Chemistry, Biology, and Materials Science, as well as nonlinear X-ray science.
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Affiliation(s)
- Rafael Abela
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Paul Beaud
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Jeroen A van Bokhoven
- Laboratory for Catalysis and Sustainable Chemistry, Paul-Scherrer Institute, 5232 Villigen PSI, and Department of Chemistry, ETH-Zürich, 8093 Zürich, Switzerland
| | - Majed Chergui
- Laboratoire de Spectroscopie Ultrarapide (LSU) and Lausanne Centre for Ultrafast Science (LACUS), Ecole Polytechnique Fédérale de Lausanne (EPFL), ISIC-FSB, Station 6, 1015 Lausanne, Switzerland
| | - Thomas Feurer
- Institute of Applied Physics, University of Bern, Bern, Switzerland
| | - Johannes Haase
- Laboratory for Catalysis and Sustainable Chemistry, Paul-Scherrer Institute, 5232 Villigen PSI, and Department of Chemistry, ETH-Zürich, 8093 Zürich, Switzerland
| | - Gerhard Ingold
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Steven L Johnson
- Institute for Quantum Electronics, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zurich, Switzerland
| | - Gregor Knopp
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Henrik Lemke
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Chris J Milne
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Bill Pedrini
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Peter Radi
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | - Jörg Standfuss
- Division of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Urs Staub
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Luc Patthey
- SwissFEL, Paul-Scherrer Institute, 5232 Villigen PSI, Switzerland
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19
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Nicoletti D, Casandruc E, Fu D, Giraldo-Gallo P, Fisher IR, Cavalleri A. Anomalous relaxation kinetics and charge-density-wave correlations in underdoped BaPb 1-x Bi x O 3. Proc Natl Acad Sci U S A 2017; 114:9020-5. [PMID: 28790181 DOI: 10.1073/pnas.1707079114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
We present measurements of transient photoconductivity in BaPb1−xBixO3 (BPBO)––a poorly understood material belonging to the bismuthate family, which has been coined “the other high-temperature superconductor.” The phase diagram of BPBO encompasses charge-density-wave (CDW) order in BaBiO3 (x = 1), through superconductivity for intermediate compositions, to bad metal behavior in BaPbO3 (x = 0). We present evidence for the coexistence of CDW order and superconductivity for underdoped compositions of BPBO––something that has been discussed previously, but never definitively established. These results are especially timely given that CDW correlations have recently been found in some underdoped cuprate superconductors, pointing toward a surprising commonality between some aspects of these materials. Our measurements also put energy scales on the associated charge order. Superconductivity often emerges in proximity of other symmetry-breaking ground states, such as antiferromagnetism or charge-density-wave (CDW) order. However, the subtle interrelation of these phases remains poorly understood, and in some cases even the existence of short-range correlations for superconducting compositions is uncertain. In such circumstances, ultrafast experiments can provide new insights by tracking the relaxation kinetics following excitation at frequencies related to the broken-symmetry state. Here, we investigate the transient terahertz conductivity of BaPb1−xBixO3––a material for which superconductivity is “adjacent” to a competing CDW phase––after optical excitation tuned to the CDW absorption band. In insulating BaBiO3 we observed an increase in conductivity and a subsequent relaxation, which are consistent with quasiparticles injection across a rigid semiconducting gap. In the doped compound BaPb0.72Bi0.28O3 (superconducting below TC = 7 K), a similar response was also found immediately above TC. This observation evidences the presence of a robust gap up to T≃ 40 K, which is presumably associated with short-range CDW correlations. A qualitatively different behavior was observed in the same material for T≳ 40 K. Here, the photoconductivity was dominated by an enhancement in carrier mobility at constant density, suggestive of melting of the CDW correlations rather than excitation across an optical gap. The relaxation displayed a temperature-dependent, Arrhenius-like kinetics, suggestive of the crossing of a free-energy barrier between two phases. These results support the existence of short-range CDW correlations above TC in underdoped BaPb1−xBixO3, and provide information on the dynamical interplay between superconductivity and charge order.
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20
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Mankowsky R, Liu B, Rajasekaran S, Liu HY, Mou D, Zhou XJ, Merlin R, Först M, Cavalleri A. Dynamical Stability Limit for the Charge Density Wave in K_{0.3}MoO_{3}. Phys Rev Lett 2017; 118:116402. [PMID: 28368632 DOI: 10.1103/physrevlett.118.116402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Indexed: 06/07/2023]
Abstract
We study the response of the one-dimensional charge density wave in K_{0.3}MoO_{3} to different types of excitation with femtosecond optical pulses. We compare direct excitation of the lattice at midinfrared frequencies with injection of quasiparticles across the low energy charge density wave gap and with charge transfer excitation in the near infrared. For all three cases, we observe a fluence threshold above which the amplitude-mode oscillation frequency is softened and the mode becomes increasingly damped. We show that all the data can be collapsed onto a universal curve in which the melting of the charge density wave occurs abruptly at a critical lattice excursion. These data highlight the existence of a universal stability limit for a charge density wave, reminiscent of the Lindemann criterion for the melting of a crystal lattice.
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Affiliation(s)
- R Mankowsky
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- University of Hamburg, 22761 Hamburg, Germany
| | - B Liu
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - S Rajasekaran
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - H Y Liu
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - D Mou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - X J Zhou
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - R Merlin
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - M Först
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - A Cavalleri
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
- University of Hamburg, 22761 Hamburg, Germany
- Department of Physics, Oxford University, Clarendon Laboratory, Oxford OX1 3PU, United Kingdom
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21
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Abstract
We review some recent advances in the use of optical fields at terahertz frequencies to drive the lattice of complex materials. We will focus on the control of low energy collective properties of solids, which emerge on average when a high frequency vibration is driven and a new crystal structure induced. We first discuss the fundamentals of these lattice rearrangements, based on how anharmonic mode coupling transforms an oscillatory motion into a quasi-static deformation of the crystal structure. We then discuss experiments, in which selectively changing a bond angle turns an insulator into a metal, accompanied by changes in charge, orbital and magnetic order. We then address the case of light induced non-equilibrium superconductivity, a mysterious phenomenon observed in some cuprates and molecular materials when certain lattice vibrations are driven. Finally, we show that the dynamics of electronic and magnetic phase transitions in complex-oxide heterostructures follow distinctly new physical pathways in case of the resonant excitation of a substrate vibrational mode.
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Affiliation(s)
- Roman Mankowsky
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
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22
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Gu M, Rondinelli JM. Ultrafast Band Engineering and Transient Spin Currents in Antiferromagnetic Oxides. Sci Rep 2016; 6:25121. [PMID: 27126354 PMCID: PMC4850389 DOI: 10.1038/srep25121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 04/11/2016] [Indexed: 11/28/2022] Open
Abstract
We report a dynamic structure and band engineering strategy with experimental protocols to induce indirect-to-direct band gap transitions and coherently oscillating pure spin-currents in three-dimensional antiferromagnets (AFM) using selective phononic excitations. In the Mott insulator LaTiO3, we show that a photo-induced nonequilibrium phonon mode amplitude destroys the spin and orbitally degenerate ground state, reduces the band gap by 160 meV and renormalizes the carrier masses. The time scale of this process is a few hundreds of femtoseconds. Then in the hole-doped correlated metallic titanate, we show how pure spin-currents can be achieved to yield spin-polarizations exceeding those observed in classic semiconductors. Last, we demonstrate the generality of the approach by applying it to the non-orbitally degenerate AFM CaMnO3. These results advance our understanding of electron-lattice interactions in structures out-of-equilibrium and establish a rational framework for designing dynamic phases that may be exploited in ultrafast optoelectronic and optospintronic devices.
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Affiliation(s)
- Mingqiang Gu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - James M. Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
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23
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Mitrano M, Cantaluppi A, Nicoletti D, Kaiser S, Perucchi A, Lupi S, Di Pietro P, Pontiroli D, Riccò M, Clark SR, Jaksch D, Cavalleri A. Possible light-induced superconductivity in K3C60 at high temperature. Nature 2016; 530:461-4. [PMID: 26855424 DOI: 10.1038/nature16522] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 12/04/2015] [Indexed: 11/20/2022]
Abstract
The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects like the optical enhancement of superconductivity 1 . Recently, nonlinear excitation 2 , 3 of certain phonons in bilayer cuprates was shown to induce superconducting-like optical properties at temperatures far above Tc4,5,6. This effect was accompanied by the disruption of competing charge-density-wave correlations7,8, which explained some but not all of the experimental results. Here, we report a similar phenomenon in a very different compound. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. Strikingly, these same signatures are observed at equilibrium when cooling metallic K3C60 below the superconducting transition temperature (Tc = 20 K). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this scenario as a possible explanation of our results.
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24
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Sadler JD, Nathvani R, Oleśkiewicz P, Ceurvorst LA, Ratan N, Kasim MF, Trines RM, Bingham R, Norreys PA. Compression of X-ray Free Electron Laser Pulses to Attosecond Duration. Sci Rep 2015; 5:16755. [PMID: 26568520 DOI: 10.1038/srep16755] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/20/2015] [Indexed: 11/30/2022] Open
Abstract
State of the art X-ray Free Electron Laser facilities currently provide the brightest X-ray pulses available, typically with mJ energy and several hundred femtosecond duration. Here we present one- and two-dimensional Particle-in-Cell simulations, utilising the process of stimulated Raman amplification, showing that these pulses are compressed to a temporally coherent, sub-femtosecond pulse at 8% efficiency. Pulses of this type may pave the way for routine time resolution of electrons in nm size potentials. Furthermore, evidence is presented that significant Landau damping and wave-breaking may be beneficial in distorting the rear of the interaction and further reducing the final pulse duration.
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25
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Minitti MP, Robinson JS, Coffee RN, Edstrom S, Gilevich S, Glownia JM, Granados E, Hering P, Hoffmann MC, Miahnahri A, Milathianaki D, Polzin W, Ratner D, Tavella F, Vetter S, Welch M, White WE, Fry AR. Optical laser systems at the Linac Coherent Light Source. J Synchrotron Radiat 2015; 22:526-31. [PMID: 25931064 PMCID: PMC4416671 DOI: 10.1107/s1600577515006244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 03/26/2015] [Indexed: 05/06/2023]
Abstract
Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump-probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump-probe experiments to be performed at LCLS.
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Affiliation(s)
- Michael P. Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Joseph S. Robinson
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Ryan N. Coffee
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Steve Edstrom
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Sasha Gilevich
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - James M. Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Eduardo Granados
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Philippe Hering
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Matthias C. Hoffmann
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Alan Miahnahri
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Despina Milathianaki
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Wayne Polzin
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Daniel Ratner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Franz Tavella
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Sharon Vetter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Marc Welch
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - William E. White
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Alan R. Fry
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
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26
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Turner JJ, Dakovski GL, Hoffmann MC, Hwang HY, Zarem A, Schlotter WF, Moeller S, Minitti MP, Staub U, Johnson S, Mitra A, Swiggers M, Noonan P, Curiel GI, Holmes M. Combining THz laser excitation with resonant soft X-ray scattering at the Linac Coherent Light Source. J Synchrotron Radiat 2015; 22:621-5. [PMID: 25931077 PMCID: PMC4416678 DOI: 10.1107/s1600577515005998] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/24/2015] [Indexed: 05/10/2023]
Abstract
This paper describes the development of new instrumentation at the Linac Coherent Light Source for conducting THz excitation experiments in an ultra high vacuum environment probed by soft X-ray diffraction. This consists of a cantilevered, fully motorized mirror system which can provide 600 kV cm(-1) electric field strengths across the sample and an X-ray detector that can span the full Ewald sphere with in-vacuum motion. The scientific applications motivated by this development, the details of the instrument, and spectra demonstrating the field strengths achieved using this newly developed system are discussed.
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Affiliation(s)
- Joshua J. Turner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Georgi L. Dakovski
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Matthias C. Hoffmann
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Harold Y. Hwang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alex Zarem
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - William F. Schlotter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Stefan Moeller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Michael P. Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Urs Staub
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Steven Johnson
- ETH Zurich, Institute for Quantum Electronics, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland
| | - Ankush Mitra
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Michele Swiggers
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Peter Noonan
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - G. Ivan Curiel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Michael Holmes
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
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Abstract
CONSPECTUS: Driving phase changes by selective optical excitation of specific vibrational modes in molecular and condensed phase systems has long been a grand goal for laser science. However, phase control has to date primarily been achieved by using coherent light fields generated by femtosecond pulsed lasers at near-infrared or visible wavelengths. This field is now being advanced by progress in generating intense femtosecond pulses in the mid-infrared, which can be tuned into resonance with infrared-active crystal lattice modes of a solid. Selective vibrational excitation is particularly interesting in complex oxides with strong electronic correlations, where even subtle modulations of the crystallographic structure can lead to colossal changes of the electronic and magnetic properties. In this Account, we summarize recent efforts to control the collective phase state in solids through mode-selective lattice excitation. The key aspect of the underlying physics is the nonlinear coupling of the resonantly driven phonon to other (Raman-active) modes due to lattice anharmonicities, theoretically discussed as ionic Raman scattering in the 1970s. Such nonlinear phononic excitation leads to rectification of a directly excited infrared-active mode and to a net displacement of the crystal along the coordinate of all anharmonically coupled modes. We present the theoretical basis and the experimental demonstration of this phenomenon, using femtosecond optical spectroscopy and ultrafast X-ray diffraction at a free electron laser. The observed nonlinear lattice dynamics is shown to drive electronic and magnetic phase transitions in many complex oxides, including insulator-metal transitions, charge/orbital order melting and magnetic switching in manganites. Furthermore, we show that the selective vibrational excitation can drive high-TC cuprates into a transient structure with enhanced superconductivity. The combination of nonlinear phononics with ultrafast crystallography at X-ray free electron lasers may provide new design rules for the development of materials that exhibit these exotic behaviors also at equilibrium.
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Affiliation(s)
- M. Först
- Max-Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
- Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - R. Mankowsky
- Max-Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
- Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - A. Cavalleri
- Max-Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
- Center for Free Electron Laser Science, Hamburg 22761, Germany
- Department of Physics, Oxford University, Clarendon Laboratory, Oxford OX1 3PU, U.K
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28
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Mankowsky R, Subedi A, Först M, Mariager SO, Chollet M, Lemke HT, Robinson JS, Glownia JM, Minitti MP, Frano A, Fechner M, Spaldin NA, Loew T, Keimer B, Georges A, Cavalleri A. Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5. Nature 2015; 516:71-3. [PMID: 25471882 DOI: 10.1038/nature13875] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/19/2014] [Indexed: 11/09/2022]
Abstract
Terahertz-frequency optical pulses can resonantly drive selected vibrational modes in solids and deform their crystal structures. In complex oxides, this method has been used to melt electronic order, drive insulator-to-metal transitions and induce superconductivity. Strikingly, coherent interlayer transport strongly reminiscent of superconductivity can be transiently induced up to room temperature (300 kelvin) in YBa2Cu3O6+x (refs 9, 10). Here we report the crystal structure of this exotic non-equilibrium state, determined by femtosecond X-ray diffraction and ab initio density functional theory calculations. We find that nonlinear lattice excitation in normal-state YBa2Cu3O6+x at above the transition temperature of 52 kelvin causes a simultaneous increase and decrease in the Cu-O2 intra-bilayer and, respectively, inter-bilayer distances, accompanied by anisotropic changes in the in-plane O-Cu-O bond buckling. Density functional theory calculations indicate that these motions cause drastic changes in the electronic structure. Among these, the enhancement in the character of the in-plane electronic structure is likely to favour superconductivity.
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Affiliation(s)
- R Mankowsky
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] University of Hamburg, 22761 Hamburg, Germany [3] Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany
| | - A Subedi
- Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France
| | - M Först
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany
| | - S O Mariager
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - M Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park 94025, California, USA
| | - H T Lemke
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park 94025, California, USA
| | - J S Robinson
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park 94025, California, USA
| | - J M Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park 94025, California, USA
| | - M P Minitti
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park 94025, California, USA
| | - A Frano
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - M Fechner
- Materials Theory, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - N A Spaldin
- Materials Theory, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - T Loew
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - B Keimer
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - A Georges
- 1] Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France [2] Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France [3] Département de Physique de la Matière Condensée (MaNEP), Université de Genève, 1211 Genève, Switzerland
| | - A Cavalleri
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] University of Hamburg, 22761 Hamburg, Germany [3] Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany [4] Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, UK
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