1
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Mattern M, von Reppert A, Zeuschner SP, Herzog M, Pudell JE, Bargheer M. Concepts and use cases for picosecond ultrasonics with x-rays. PHOTOACOUSTICS 2023; 31:100503. [PMID: 37275326 PMCID: PMC10238750 DOI: 10.1016/j.pacs.2023.100503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/28/2023] [Accepted: 04/30/2023] [Indexed: 06/07/2023]
Abstract
This review discusses picosecond ultrasonics experiments using ultrashort hard x-ray probe pulses to extract the transient strain response of laser-excited nanoscopic structures from Bragg-peak shifts. This method provides direct, layer-specific, and quantitative information on the picosecond strain response for structures down to few-nm thickness. We model the transient strain using the elastic wave equation and express the driving stress using Grüneisen parameters stating that the laser-induced stress is proportional to energy density changes in the microscopic subsystems of the solid, i.e., electrons, phonons and spins. The laser-driven strain response can thus serve as an ultrafast proxy for local energy-density and temperature changes, but we emphasize the importance of the nanoscale morphology for an accurate interpretation due to the Poisson effect. The presented experimental use cases encompass ultrathin and opaque metal-heterostructures, continuous and granular nanolayers as well as negative thermal expansion materials, that each pose a challenge to established all-optical techniques.
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Affiliation(s)
- Maximilian Mattern
- Institut für Physik & Astronomie, Universität Potsdam, 14476 Potsdam, Germany
| | | | - Steffen Peer Zeuschner
- Institut für Physik & Astronomie, Universität Potsdam, 14476 Potsdam, Germany
- Helmholtz Zentrum Berlin, 12489 Berlin, Germany
| | - Marc Herzog
- Institut für Physik & Astronomie, Universität Potsdam, 14476 Potsdam, Germany
| | - Jan-Etienne Pudell
- Institut für Physik & Astronomie, Universität Potsdam, 14476 Potsdam, Germany
- Helmholtz Zentrum Berlin, 12489 Berlin, Germany
- European XFEL, 22869 Schenefeld, Germany
| | - Matias Bargheer
- Institut für Physik & Astronomie, Universität Potsdam, 14476 Potsdam, Germany
- Helmholtz Zentrum Berlin, 12489 Berlin, Germany
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2
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Liu B, Xiao H, Weinelt M. Microscopic insights to spin transport-driven ultrafast magnetization dynamics in a Gd/Fe bilayer. SCIENCE ADVANCES 2023; 9:eade0286. [PMID: 37196076 DOI: 10.1126/sciadv.ade0286] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 04/13/2023] [Indexed: 05/19/2023]
Abstract
Laser-induced spin transport is a key ingredient in ultrafast spin dynamics. However, it remains debated to what extent ultrafast magnetization dynamics generates spin currents and vice versa. We use time- and spin-resolved photoemission spectroscopy to study an antiferromagnetically coupled Gd/Fe bilayer, a prototype system for all-optical switching. Spin transport leads to an ultrafast drop of the spin polarization at the Gd surface, demonstrating angular-momentum transfer over several nanometers. Thereby, Fe acts as spin filter, absorbing spin majority but reflecting spin minority electrons. Spin transport from Gd to Fe was corroborated by an ultrafast increase of the Fe spin polarization in a reversed Fe/Gd bilayer. In contrast, for a pure Gd film, spin transport into the tungsten substrate can be neglected, as spin polarization stays constant. Our results suggest that ultrafast spin transport drives the magnetization dynamics in Gd/Fe and reveal microscopic insights into ultrafast spin dynamics.
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Affiliation(s)
- Bo Liu
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Huijuan Xiao
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Martin Weinelt
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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3
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Gu M, Bai YH, Zhang GP, George TF. Spin-phonon dispersion in magnetic materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:375802. [PMID: 35793694 DOI: 10.1088/1361-648x/ac7f17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Microscopic coupling between the electron spin and the lattice vibration is responsible for an array of exotic properties from morphic effects in simple non magnets to magnetodielectric coupling in multiferroic spinels and hematites. Traditionally, a single spin-phonon coupling constant is used to characterize how effectively the lattice can affect the spin, but it is hardly enough to capture novel electromagnetic behaviors to the full extent. Here, we introduce a concept of spin-phonon dispersion to project the spin moment change along the phonon crystal momentum direction, so the entire spin change can be mapped out. Different from the phonon dispersion, the spin-phonon dispersion has both positive and negative frequency branches even in the equilibrium ground state, which correspond to the spin enhancement and spin reduction, respectively. Our study of bcc Fe and hcp Co reveals that the spin force matrix, that is, the second-order spatial derivative of spin moment, is similar to the vibrational force matrix, but its diagonal elements are smaller than the off-diagonal ones. This leads to the distinctive spin-phonon dispersion. The concept of spin-phonon dispersion expands the traditional Elliott-Yafet theory in nonmagnetic materials to the entire Brillouin zone in magnetic materials, thus opening the door to excited states in systems such as CoF2and NiO, where a strong spin-lattice coupling is detected in the THz regime.
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Affiliation(s)
- Mingqiang Gu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Y H Bai
- Office of Information Technology, Indiana State University, Terre Haute, IN 47809, United States of America
| | - G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
| | - Thomas F George
- Departments of Chemistry & Biochemistry and Physics & Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121, United States of America
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4
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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. NATURE MATERIALS 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] [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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5
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Bykov AY, Shukla A, van Schilfgaarde M, Green MA, Zayats AV. Ultrafast Carrier and Lattice Dynamics in Plasmonic Nanocrystalline Copper Sulfide Films. LASER & PHOTONICS REVIEWS 2021; 15:2000346. [PMID: 34484456 PMCID: PMC8408971 DOI: 10.1002/lpor.202000346] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/29/2020] [Indexed: 05/26/2023]
Abstract
Excited carrier dynamics in plasmonic nanostructures determines many important optical properties such as nonlinear optical response and photocatalytic activity. Here it is shown that mesoscopic plasmonic covellite nanocrystals with low free-carrier concentration exhibit a much faster carrier relaxation than in traditional plasmonic materials. A nonequilibrium hot-carrier population thermalizes within first 20 fs after photoexcitation. A decreased thermalization time in nanocrystals compared to a bulk covellite is consistent with the reduced Coulomb screening in ultrathin films. The subsequent relaxation of thermalized, equilibrium electron gas is faster than in traditional plasmonic metals due to the lower carrier concentration and agrees well with that in a bulk covellite showing no evidence of quantum confinement or hot-hole trapping at the surface states. The excitation of coherent optical phonon modes in a covellite is also demonstrated, revealing coherent lattice dynamics in plasmonic materials, which until now was mainly limited to dielectrics, semiconductors, and semimetals. These findings show advantages of this new mesoscopic plasmonic material for active control of optical processes.
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Affiliation(s)
- Anton Yu. Bykov
- Department of Physics and London Centre for NanotechnologyKing's College LondonLondonWS2R 2LSUK
| | - Amaresh Shukla
- Department of Physics and London Centre for NanotechnologyKing's College LondonLondonWS2R 2LSUK
| | - Mark van Schilfgaarde
- Department of Physics and London Centre for NanotechnologyKing's College LondonLondonWS2R 2LSUK
- Prof. M. van SchilfgaardeNational Renewable Energy LaboratoryGoldenColorado80401USA
| | - Mark A. Green
- Department of Physics and London Centre for NanotechnologyKing's College LondonLondonWS2R 2LSUK
| | - Anatoly V. Zayats
- Department of Physics and London Centre for NanotechnologyKing's College LondonLondonWS2R 2LSUK
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6
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Ron A, Chaudhary S, Zhang G, Ning H, Zoghlin E, Wilson SD, Averitt RD, Refael G, Hsieh D. Ultrafast Enhancement of Ferromagnetic Spin Exchange Induced by Ligand-to-Metal Charge Transfer. PHYSICAL REVIEW LETTERS 2020; 125:197203. [PMID: 33216570 DOI: 10.1103/physrevlett.125.197203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 08/17/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground state. We demonstrate this effect in the layered ferromagnetic insulator CrSiTe_{3} by exciting Te-to-Cr charge-transfer transitions using ultrashort laser pulses and detecting coherent phonon oscillations that are impulsively generated by superexchange enhancement via magneto-elastic coupling. This mechanism kicks in below the temperature scale where short-range in-plane spin correlations begin to develop and disappears when the excitation energy is tuned away from the charge-transfer resonance, consistent with our predictions.
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Affiliation(s)
- A Ron
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - S Chaudhary
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - G Zhang
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - H Ning
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - E Zoghlin
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - S D Wilson
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - R D Averitt
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - G Refael
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - D Hsieh
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
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7
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Guo J, Liang W, Luo SN. Anomalous Hot Carrier Decay in Ferromagnetic Cr 2Ge 2Te 6 via Spin-Phonon Coupling. J Phys Chem Lett 2020; 11:9351-9357. [PMID: 33090787 DOI: 10.1021/acs.jpclett.0c02872] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The link between spin-phonon coupling (SPC) and coherent phonon excitation as well as hot carrier decay dynamics is investigated with femtosecond transient optical spectroscopy. Coherent phonon excitation via SPC is directly observed in a van der Waals ferromagnet Cr2Ge2Te6 (CGT). Such coherent phonon excitation is strongly dependent on spin ordering of CGT and facilitates considerably hot carrier decay. While hot carriers decay normally via direct electron-phonon coupling, hot carrier decay in ferromagnetic CGT is also achieved via indirect electron-phonon coupling, with spin ordering acting as the intermediate between hot carriers and coherent phonons.
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Affiliation(s)
- Jia Guo
- The Peac Institute of Multiscale Sciences, Chengdu 610031, Sichuan, People's Republic of China
| | - Weizheng Liang
- The Peac Institute of Multiscale Sciences, Chengdu 610031, Sichuan, People's Republic of China
| | - Sheng-Nian Luo
- School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, People's Republic of China
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8
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Mikhaylovskiy RV, Huisman TJ, Gavrichkov VA, Polukeev SI, Ovchinnikov SG, Afanasiev D, Pisarev RV, Rasing T, Kimel AV. Resonant Pumping of d-d Crystal Field Electronic Transitions as a Mechanism of Ultrafast Optical Control of the Exchange Interactions in Iron Oxides. PHYSICAL REVIEW LETTERS 2020; 125:157201. [PMID: 33095611 DOI: 10.1103/physrevlett.125.157201] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
The microscopic origin of ultrafast modification of the ratio between the symmetric (J) and antisymmetric (D) exchange interaction in antiferromagnetic iron oxides is revealed, using femtosecond laser excitation as a pump and terahertz emission spectroscopy as a probe. By tuning the photon energy of the laser pump pulse we show that the effect of light on the D/J ratio in two archetypical iron oxides FeBO_{3} and ErFeO_{3} is maximized when the photon energy is in resonance with a spin and parity forbidden d-d transition between the crystal-field split states of Fe^{3+} ions. The experimental findings are supported by a multielectron model, which accounts for the resonant absorption of photons by Fe^{3+} ions. Our results reveal the importance of the parity and spin-change forbidden, and therefore often underestimated, d-d transitions in ultrafast optical control of magnetism.
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Affiliation(s)
- R V Mikhaylovskiy
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YW, United Kingdom
| | - T J Huisman
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - V A Gavrichkov
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
| | - S I Polukeev
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
| | - S G Ovchinnikov
- Kirensky Institute of Physics, Federal Research Center KSC SB RAS, 660036 Krasnoyarsk, Russia
| | - D Afanasiev
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - R V Pisarev
- Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Th Rasing
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - A V Kimel
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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9
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Tracking the ultrafast motion of an antiferromagnetic order parameter. Nat Commun 2019; 10:3995. [PMID: 31488834 PMCID: PMC6728322 DOI: 10.1038/s41467-019-11961-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 08/06/2019] [Indexed: 11/29/2022] Open
Abstract
The unique functionalities of antiferromagnets offer promising routes to advance information technology. Their compensated magnetic order leads to spin resonances in the THz-regime, which suggest the possibility to coherently control antiferromagnetic (AFM) devices orders of magnitude faster than traditional electronics. However, the required time resolution, complex sublattice interactions and the relative inaccessibility of the AFM order parameter pose serious challenges to studying AFM spin dynamics. Here, we reveal the temporal evolution of an AFM order parameter directly in the time domain. We modulate the AFM order in hexagonal YMnO3 by coherent magnon excitation and track the ensuing motion of the AFM order parameter using time-resolved optical second-harmonic generation. The dynamic symmetry reduction by the moving order parameter allows us to separate electron dynamics from spin dynamics. As transient symmetry reductions are common to coherent excitations, we have a general tool for tracking the ultrafast motion of an AFM order parameter. Understanding antiferromagnetic dynamics enables future information technologies, but the detection remains challenging. Here, the authors show the capability of tracking the three dimensional spin motions in YMnO3 by combining time resolved measurements of Faraday rotation and magneto-optical second harmonic generation.
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10
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Chen J, Bovensiepen U, Eschenlohr A, Müller T, Elliott P, Gross EKU, Dewhurst JK, Sharma S. Competing Spin Transfer and Dissipation at Co/Cu(001) Interfaces on Femtosecond Timescales. PHYSICAL REVIEW LETTERS 2019; 122:067202. [PMID: 30822073 DOI: 10.1103/physrevlett.122.067202] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 11/28/2018] [Indexed: 05/23/2023]
Abstract
By combining interface-sensitive nonlinear magneto-optical experiments with femtosecond time resolution and ab initio time-dependent density functional theory, we show that optically excited spin dynamics at Co/Cu(001) interfaces proceeds via spin-dependent charge transfer and back transfer between Co and Cu. This ultrafast spin transfer competes with dissipation of spin angular momentum mediated by spin-orbit coupling already on sub 100 fs timescales. We thereby identify the fundamental microscopic processes during laser-induced spin transfer at a model interface for technologically relevant ferromagnetic heterostructures.
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Affiliation(s)
- J Chen
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
| | - U Bovensiepen
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
| | - A Eschenlohr
- Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
| | - T Müller
- Theory Department, Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - P Elliott
- Theory Department, Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - E K U Gross
- Theory Department, Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - J K Dewhurst
- Theory Department, Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - S Sharma
- Theory Department, Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany and Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489 Berlin, Germany
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11
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Zhang GP, Jenkins T, Bennett M, Bai YH. Manifestation of intra-atomic 5d6s-4f exchange coupling in photoexcited gadolinium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:495807. [PMID: 29105644 DOI: 10.1088/1361-648x/aa986c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intra-atomic exchange couplings (IECs) between 5d6s and 4f electrons are ubiquitous in rare-earth metals and play a critical role in spin dynamics. However, detecting them in real time domain has been difficult. Here we show the direct evidence of IEC between 5d6s and 4f electrons in gadolinium. Upon femtosecond laser excitation, 5d6s electrons are directly excited; their majority bands shift toward the Fermi level while their minority bands do the opposite. For the first time, our first-principles minority shift now agrees with the experiment quantitatively. Excited 5d6s electrons lower the exchange potential barrier for 4f electrons, so the 4f states are also shifted in energy, a prediction that can be tested experimentally. Although a significant number of 5d6s electrons, some several eV below the Fermi level, are excited out of the Fermi sea, there is no change in the 4f states, a clear manifestation of intra-atomic exchange coupling.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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12
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Mentink JH. Manipulating magnetism by ultrafast control of the exchange interaction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:453001. [PMID: 28990577 DOI: 10.1088/1361-648x/aa8abf] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In recent years, the optical control of exchange interactions has emerged as an exciting new direction in the study of the ultrafast optical control of magnetic order. Here we review recent theoretical works on antiferromagnetic systems, devoted to (i) simulating the ultrafast control of exchange interactions, (ii) modeling the strongly nonequilibrium response of the magnetic order and (iii) the relation with relevant experimental works developed in parallel. In addition to the excitation of spin precession, we discuss examples of rapid cooling and the control of ultrafast coherent longitudinal spin dynamics in response to femtosecond optically induced perturbations of exchange interactions. These elucidate the potential for exploiting the control of exchange interactions to find new scenarios for both faster and more energy-efficient manipulation of magnetism.
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Affiliation(s)
- J H Mentink
- Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ, Nijmegen, Netherlands
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13
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Bierbrauer U, Weber ST, Schummer D, Barkowski M, Mahro AK, Mathias S, Christian Schneider H, Stadtmüller B, Aeschlimann M, Rethfeld B. Ultrafast magnetization dynamics in Nickel: impact of pump photon energy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:244002. [PMID: 28510535 DOI: 10.1088/1361-648x/aa6f73] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Magnetization dynamics on a femtosecond timescale has been observed for a huge variety of magnetic structures. However, the influence of different excitation photon energies has not been studied in detail yet. In our time-resolved magneto-optical Kerr effect setup we excite a Nickel bulk system with 1.55 and 3.1 eV, respectively, leading to different remagnetization dynamics depending on the chosen photon energy. Furthermore we complement our experimental data with a theoretical approach applying appropriate Boltzmann collision integrals including the density of states of Nickel. The comparison between the experimental data and the theoretical approach indicates that photon-energy dependent transport processes play a major role in this setup.
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Affiliation(s)
- Ute Bierbrauer
- Department of Physics and OPTIMAS Research Center, University of Kaiserslautern, Erwin-Schrödinger-Strasse 46, 67663 Kaiserslautern, Germany
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14
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Andres B, Christ M, Gahl C, Wietstruk M, Weinelt M, Kirschner J. Separating Exchange Splitting from Spin Mixing in Gadolinium by Femtosecond Laser Excitation. PHYSICAL REVIEW LETTERS 2015; 115:207404. [PMID: 26613472 DOI: 10.1103/physrevlett.115.207404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Indexed: 06/05/2023]
Abstract
Employing spin-, time-, and energy-resolved photoemission spectroscopy, we present the first study on the spin polarization of a single electronic state after ultrafast optical excitation. Our investigation concentrates on the majority-spin component of the d-band-derived Gd(0001) surface state d(z(2))(↑). While its binding energy shows a rapid Stoner-like shift by 90 meV with an exponential time constant of τ(E)=0.6±0.1 ps, the d(z(2))(↑) spin polarization remains nearly constant within the first picoseconds and decays with τ(S)=15±8 ps. This behavior is in clear contrast to the equilibrium phase transition, where the spin polarization vanishes at the Curie temperature.
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Affiliation(s)
- Beatrice Andres
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
| | - Marc Christ
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
| | - Cornelius Gahl
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
| | - Marko Wietstruk
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
| | - Martin Weinelt
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
| | - Jürgen Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle/Saale, Germany
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15
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Afanasiev D, Razdolski I, Skibinsky KM, Bolotin D, Yagupov SV, Strugatsky MB, Kirilyuk A, Rasing T, Kimel AV. Laser excitation of lattice-driven anharmonic magnetization dynamics in dielectric FeBO3. PHYSICAL REVIEW LETTERS 2014; 112:147403. [PMID: 24766012 DOI: 10.1103/physrevlett.112.147403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Indexed: 06/03/2023]
Abstract
Femtosecond laser pulses trigger in dielectric FeBO3 coherent oscillations of the magnetic anisotropy followed by spins. The oscillations are driven by optically excited lattice vibrations strongly coupled to the magnetic system. Unlike the spin resonances, this mode is characterized by a very small damping ratio and can be easily pushed into an anharmonic regime.
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Affiliation(s)
- D Afanasiev
- Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ Nijmegen, The Netherlands
| | - I Razdolski
- Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ Nijmegen, The Netherlands
| | - K M Skibinsky
- Solid-State Physics Chair, Department of Physics, Taurida National University, 95036 Simferopol, Ukraine
| | - D Bolotin
- Solid-State Physics Chair, Department of Physics, Taurida National University, 95036 Simferopol, Ukraine
| | - S V Yagupov
- Solid-State Physics Chair, Department of Physics, Taurida National University, 95036 Simferopol, Ukraine
| | - M B Strugatsky
- Solid-State Physics Chair, Department of Physics, Taurida National University, 95036 Simferopol, Ukraine
| | - A Kirilyuk
- Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ Nijmegen, The Netherlands
| | - Th Rasing
- Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ Nijmegen, The Netherlands
| | - A V Kimel
- Radboud University Nijmegen, Institute for Molecules and Materials, 6525 AJ Nijmegen, The Netherlands
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16
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Kim KW, Pashkin A, Schäfer H, Beyer M, Porer M, Wolf T, Bernhard C, Demsar J, Huber R, Leitenstorfer A. Ultrafast transient generation of spin-density-wave order in the normal state of BaFe2As2 driven by coherent lattice vibrations. NATURE MATERIALS 2012; 11:497-501. [PMID: 22484832 DOI: 10.1038/nmat3294] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 03/05/2012] [Indexed: 05/31/2023]
Abstract
The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity and high-temperature superconductivity. Strong coupling or competition between various orders in these systems presents the key to manipulate their functional properties by means of external perturbations such as electric and magnetic fields or pressure. Ultrashort and intense optical pulses have emerged as an interesting tool to investigate elementary dynamics and control material properties by melting an existing order. Here, we employ few-cycle multi-terahertz pulses to resonantly probe the evolution of the spin-density-wave (SDW) gap of the pnictide compound BaFe(2)As(2) following excitation with a femtosecond optical pulse. When starting in the low-temperature ground state, optical excitation results in a melting of the SDW order, followed by ultrafast recovery. In contrast, the SDW gap is induced when we excite the normal state above the transition temperature. Very surprisingly, the transient ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. Our results attest to a pronounced spin-phonon coupling in pnictides that supports rapid development of a macroscopic order on small vibrational displacement even without breaking the symmetry of the crystal.
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17
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Koopmans B, Malinowski G, Dalla Longa F, Steiauf D, Fähnle M, Roth T, Cinchetti M, Aeschlimann M. Explaining the paradoxical diversity of ultrafast laser-induced demagnetization. NATURE MATERIALS 2010; 9:259-65. [PMID: 20010830 DOI: 10.1038/nmat2593] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 11/03/2009] [Indexed: 05/22/2023]
Abstract
Pulsed-laser-induced quenching of ferromagnetic order has intrigued researchers since pioneering works in the 1990s. It was reported that demagnetization in gadolinium proceeds within 100 ps, but three orders of magnitude faster in ferromagnetic transition metals such as nickel. Here we show that a model based on electron-phonon-mediated spin-flip scattering explains both timescales on equal footing. Our interpretation is supported by ab initio estimates of the spin-flip scattering probability, and experimental fluence dependencies are shown to agree perfectly with predictions. A phase diagram is constructed in which two classes of laser-induced magnetization dynamics can be distinguished, where the ratio of the Curie temperature to the atomic magnetic moment turns out to have a crucial role. We conclude that the ultrafast magnetization dynamics can be well described disregarding highly excited electronic states, merely considering the thermalized electron system.
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Affiliation(s)
- B Koopmans
- Department of Applied Physics, Center for NanoMaterials (cNM), Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
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18
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Hase M, Kitajima M. Interaction of coherent phonons with defects and elementary excitations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:073201. [PMID: 21386377 DOI: 10.1088/0953-8984/22/7/073201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We present an overview of the feasibility of using coherent phonon spectroscopy to study interaction dynamics of excited lattice vibrations with their environments. By exploiting the features of coherent phonons with a pump-probe technique, one can study lattice motions in a sub-picosecond time range. The dephasing properties tell us not only about interaction dynamics with carriers (electrons and holes) or thermal phonons but also about point defects in crystals. Modulations of the coherent phonon amplitude by more than two modes are closely related to phonon-carrier or phonon-phonon interferences. Related to this phenomenon, formation of coherent phonons at higher harmonics gives direct evidence for phonon-phonon couplings. A combined study of coherent phonons and ultrafast carrier response can be useful for understanding phonon-carrier interaction dynamics. For metals like zinc, nonequilibrium electrons may dominate the dynamics of both relaxation and generation of coherent phonons. The frequency chirp of coherent phonons can be a direct measure of how and when phonon-phonon and phonon-carrier couplings occur. Carbon nanotubes show some complicated behavior due to the existence of many modes with different symmetries, resulting in superposition or interference. To illustrate one of the most interesting applications, the selective excitation of specific phonon modes through the use of a pulse train technique is shown.
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Affiliation(s)
- Muneaki Hase
- Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8573, Japan.
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19
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Coherent Lattice Oscillations in Solids and Their Optical Control. SPRINGER SERIES IN CHEMICAL PHYSICS 2010. [DOI: 10.1007/978-3-642-03825-9_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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20
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Itoh N, Duffy DM, Khakshouri S, Stoneham AM. Making tracks: electronic excitation roles in forming swift heavy ion tracks. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:474205. [PMID: 21832484 DOI: 10.1088/0953-8984/21/47/474205] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Swift heavy ions cause material modification along their tracks, changes primarily due to their very dense electronic excitation. The available data for threshold stopping powers indicate two main classes of materials. Group I, with threshold stopping powers above about 10 keV nm(-1), includes some metals, crystalline semiconductors and a few insulators. Group II, with lower thresholds, comprises many insulators, amorphous materials and high T(c) oxide superconductors. We show that the systematic differences in behaviour result from different coupling of the dense excited electrons, holes and excitons to atomic (ionic) motions, and the consequent lattice relaxation. The coupling strength of excitons and charge carriers with the lattice is crucial. For group II, the mechanism appears to be the self-trapped exciton model of Itoh and Stoneham (1998 Nucl. Instrum. Methods Phys. Res. B 146 362): the local structural changes occur roughly when the exciton concentration exceeds the number of lattice sites. In materials of group I, excitons are not self-trapped and structural change requires excitation of a substantial fraction of bonding electrons, which induces spontaneous lattice expansion within a few hundred femtoseconds, as recently observed by laser-induced time-resolved x-ray diffraction of semiconductors. Our analysis addresses a number of experimental results, such as track morphology, the efficiency of track registration and the ratios of the threshold stopping power of various materials.
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Affiliation(s)
- N Itoh
- 40-202 Koikecho, Meito, Nagoya 465-0047, Japan
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21
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Melnikov A, Povolotskiy A, Bovensiepen U. Magnon-enhanced phonon damping at Gd(0001) and Tb(0001) surfaces using femtosecond time-resolved optical second-harmonic generation. PHYSICAL REVIEW LETTERS 2008; 100:247401. [PMID: 18643627 DOI: 10.1103/physrevlett.100.247401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Indexed: 05/26/2023]
Abstract
Damping of coherent optical phonons is investigated by femtosecond time-resolved second-harmonic generation at Gd(0001) and Tb(0001) surfaces. At low temperature the damping rate increases monotonically with temperature, but close to the Curie point the damping rate is strongly reduced. We explain this behavior by phonon-magnon scattering originating from spin-orbit coupling proven by a larger effect for Tb than for Gd. Consideration of phonon-electron and phonon-phonon scattering shows that magnon-mediated damping is dominant almost up to the Curie temperature.
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Affiliation(s)
- A Melnikov
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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22
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Melnikov A, Prima-Garcia H, Lisowski M, Giessel T, Weber R, Schmidt R, Gahl C, Bulgakova NM, Bovensiepen U, Weinelt M. Nonequilibrium magnetization dynamics of gadolinium studied by magnetic linear dichroism in time-resolved 4f core-level photoemission. PHYSICAL REVIEW LETTERS 2008; 100:107202. [PMID: 18352227 DOI: 10.1103/physrevlett.100.107202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Indexed: 05/26/2023]
Abstract
The magnetic linear dichroism of the gadolinium 4f core level is studied in a time-resolved photoemission experiment employing laser pump- and synchrotron-radiation probe pulses. Upon optical excitation of the 5d6s valence electrons with femtosecond laser pulses, the magnetic order in the 4f spin system is reduced. Remarkably, the linear dichroism remains at 80% of the equilibrium contrast while the lattice temperature reaches the Curie temperature due to electron-phonon scattering. Contrasting itinerant ferromagnets, this shows that equilibration between the lattice and spin subsystems takes in Gd about 80 ps and is established in parallel with heat diffusion.
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Affiliation(s)
- A Melnikov
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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23
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Hsia CH, Chen TY, Son DH. Size-dependent ultrafast magnetization dynamics in iron oxide (Fe3O4) nanocrystals. NANO LETTERS 2008; 8:571-576. [PMID: 18225939 DOI: 10.1021/nl072899p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Optically induced ultrafast demagnetization and its recovery in superparamagnetic colloidal iron oxide (Fe3O4) nanocrystals have been investigated via time-resolved Faraday rotation measurements. Optical excitation with near-infrared laser pulse resulted in ultrafast demagnetization in approximately 100 fs via the destruction of ferrimagnetic ordering. The degree of demagnetization increased with the excitation density, and the complete demagnetization reached at approximately 10% excitation density. The magnetization recovered on two time scales, several picoseconds and hundreds of picoseconds, which can be associated with the initial reestablishment of the ferrimagnetic ordering and the electronic relaxation back to the ground state, respectively. The amplitude of the slower recovery component increased with the size of the nanocrystals, suggesting the size-dependent ferrimagnetic ordering throughout the volume of the nanocrystal.
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Affiliation(s)
- Chih-Hao Hsia
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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24
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Matsubara M, Okimoto Y, Ogasawara T, Tomioka Y, Okamoto H, Tokura Y. Ultrafast photoinduced insulator-ferromagnet transition in the perovskite manganite Gd0.55Sr0.45MnO3. PHYSICAL REVIEW LETTERS 2007; 99:207401. [PMID: 18233185 DOI: 10.1103/physrevlett.99.207401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Indexed: 05/15/2023]
Abstract
We have investigated the ultrafast spin and charge dynamics in the course of a photoinduced phase transition from an insulator with short-range charge order and orbital order (OO) to a ferromagnetic metal in perovskite-type Gd0.55Sr0.45MnO3. Transient reflectivity changes suggest that the metallic state is formed just after the photoirradiation and decays within approximately 1 ps. The magnetization, however, increases with the time constant of 0.5 ps and decays in approximately 10 ps. The relatively slow increase of the magnetization is attributable to the magnetic-field-induced alignment of ferromagnetic domains in the initially produced metallic state and its slow decay to the partial recovery of the OO.
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Affiliation(s)
- M Matsubara
- Correlated Electron Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8562, Japan.
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25
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Stamm C, Kachel T, Pontius N, Mitzner R, Quast T, Holldack K, Khan S, Lupulescu C, Aziz EF, Wietstruk M, Dürr HA, Eberhardt W. Femtosecond modification of electron localization and transfer of angular momentum in nickel. NATURE MATERIALS 2007; 6:740-3. [PMID: 17721541 DOI: 10.1038/nmat1985] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 07/20/2007] [Indexed: 05/16/2023]
Abstract
The rapidly increasing information density required of modern magnetic data storage devices raises the question of the fundamental limits in bit size and writing speed. At present, the magnetization reversal of a bit can occur as quickly as 200 ps (ref. 1). A fundamental limit has been explored by using intense magnetic-field pulses of 2 ps duration leading to a non-deterministic magnetization reversal. For this process, dissipation of spin angular momentum to other degrees of freedom on an ultrafast timescale is crucial. An even faster regime down to 100 fs or below might be reached by non-thermal control of magnetization with femtosecond laser radiation. Here, we show that an efficient novel channel for angular momentum dissipation to the lattice can be opened by femtosecond laser excitation of a ferromagnet. For the first time, the quenching of spin angular momentum and its transfer to the lattice with a time constant of 120+/-70 fs is determined unambiguously with X-ray magnetic circular dichroism. We report the first femtosecond time-resolved X-ray absorption spectroscopy data over an entire absorption edge, which are consistent with an unexpected increase in valence-electron localization during the first 120+/-50 fs, possibly providing the driving force behind femtosecond spin-lattice relaxation.
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Affiliation(s)
- C Stamm
- BESSY GmbH, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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26
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Stanciu CD, Hansteen F, Kimel AV, Tsukamoto A, Itoh A, Kirilyuk A, Rasing T. Ultrafast interaction of the angular momentum of photons with spins in the metallic amorphous alloy GdFeCo. PHYSICAL REVIEW LETTERS 2007; 98:207401. [PMID: 17677737 DOI: 10.1103/physrevlett.98.207401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 03/07/2007] [Indexed: 05/16/2023]
Abstract
Ultrashort laser pulses have been used to study the effect of circularly polarized light on spins in the ferrimagnetic metal GdFeCo. By turning the sample into a multidomain state and thereby suppressing the observation of the heating effect of light, we have been able to demonstrate an ultrafast nonthermal excitation of spin waves with a phase that depends on the angular momentum of the photons. These results demonstrate the possibility of ultrafast coherent control of the magnetization in this metallic system.
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Affiliation(s)
- C D Stanciu
- Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
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27
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Loukakos PA, Lisowski M, Bihlmayer G, Blügel S, Wolf M, Bovensiepen U. Dynamics of the self-energy of the Gd(0001) surface state probed by femtosecond photoemission spectroscopy. PHYSICAL REVIEW LETTERS 2007; 98:097401. [PMID: 17359194 DOI: 10.1103/physrevlett.98.097401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Indexed: 05/14/2023]
Abstract
Transient changes of the complex self-energy of the 5d(z2) surface state on Gd(0001) after intense optical excitation are investigated by femtosecond time-resolved photoemission. We observe an ultrafast (<100 fs) broadening of the linewidth due to e-e scattering followed by a decrease of the binding energy due to thermal expansion of the lattice. In addition, we resolve a periodic breathing of the band structure which originates from a coherent phonon. An amplitude of 1 pm is derived from the binding energy shift upon lattice displacement calculated by density functional theory.
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Affiliation(s)
- P A Loukakos
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin-Dahlem, Germany
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28
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Nomoto T, Onishi H. Fourth-order coherent Raman spectroscopy in a time domain: applications to buried interfaces. Phys Chem Chem Phys 2007; 9:5515-21. [DOI: 10.1039/b704566m] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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29
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Chulkov EV, Borisov AG, Gauyacq JP, Sanchez-Portal D, Silkin VM, Zhukov VP, Echenique PM. Electronic Excitations in Metals and at Metal Surfaces. Chem Rev 2006; 106:4160-206. [PMID: 17031983 DOI: 10.1021/cr050166o] [Citation(s) in RCA: 208] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E V Chulkov
- Departamento de Física de Materiales and Centro Mixto CSIC-UPV/EHU, Facultad de Ciencias Químicas, Universidad del País Vasco UPV/EHU, Apdo. 1072, 20080 San Sebastian/Donostia, Basque Country, Spain.
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30
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Matsumoto Y, Watanabe K. Coherent Vibrations of Adsorbates Induced by Femtosecond Laser Excitation. Chem Rev 2006; 106:4234-60. [PMID: 17031985 DOI: 10.1021/cr050165w] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Yoshiyasu Matsumoto
- National Institutes of Natural Sciences, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan.
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31
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Lisowski M, Loukakos PA, Melnikov A, Radu I, Ungureanu L, Wolf M, Bovensiepen U. Femtosecond electron and spin dynamics in Gd(0001) studied by time-resolved photoemission and magneto-optics. PHYSICAL REVIEW LETTERS 2005; 95:137402. [PMID: 16197177 DOI: 10.1103/physrevlett.95.137402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Indexed: 05/04/2023]
Abstract
Femtosecond electron and spin dynamics of the Gd(0001) surface are investigated by time-resolved photoemission and second harmonic generation. Upon optical excitation the spin polarization of the surface state is reduced by half while its exchange splitting remains nearly unchanged. Electron-magnon interaction is proposed to facilitate electron-spin-flip scattering among spin-mixed surface and bulk states, which provides a mechanism for ultrafast demagnetization.
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Affiliation(s)
- M Lisowski
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin-Dahlem, Germany
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