1
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Shokeen V, Heber M, Kutnyakhov D, Wang X, Yaroslavtsev A, Maldonado P, Berritta M, Wind N, Wenthaus L, Pressacco F, Min CH, Nissen M, Mahatha SK, Dziarzhytski S, Oppeneer PM, Rossnagel K, Elmers HJ, Schönhense G, Dürr HA. Real-time observation of non-equilibrium phonon-electron energy and angular momentum flow in laser-heated nickel. SCIENCE ADVANCES 2024; 10:eadj2407. [PMID: 38295169 PMCID: PMC10830112 DOI: 10.1126/sciadv.adj2407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024]
Abstract
Identifying the microscopic nature of non-equilibrium energy transfer mechanisms among electronic, spin, and lattice degrees of freedom is central to understanding ultrafast phenomena such as manipulating magnetism on the femtosecond timescale. Here, we use time- and angle-resolved photoemission spectroscopy to go beyond the often-used ensemble-averaged view of non-equilibrium dynamics in terms of quasiparticle temperature evolutions. We show for ferromagnetic Ni that the non-equilibrium electron and spin dynamics display pronounced variations with electron momentum, whereas the magnetic exchange interaction remains isotropic. This highlights the influence of lattice-mediated scattering processes and opens a pathway toward unraveling the still elusive microscopic mechanism of spin-lattice angular momentum transfer.
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Affiliation(s)
- Vishal Shokeen
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Michael Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Xiaocui Wang
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | | | - Pablo Maldonado
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Marco Berritta
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Nils Wind
- Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Lukas Wenthaus
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Chul-Hee Min
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Matz Nissen
- Institut für Experimentalphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - Sanjoy K. Mahatha
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Peter M. Oppeneer
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Hans-Joachim Elmers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Gerd Schönhense
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - Hermann A. Dürr
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
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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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Heber M, Wind N, Kutnyakhov D, Pressacco F, Arion T, Roth F, Eberhardt W, Rossnagel K. Multispectral time-resolved energy-momentum microscopy using high-harmonic extreme ultraviolet radiation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:083905. [PMID: 36050085 DOI: 10.1063/5.0091003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
A 790-nm-driven high-harmonic generation source with a repetition rate of 6 kHz is combined with a toroidal-grating monochromator and a high-detection-efficiency photoelectron time-of-flight momentum microscope to enable time- and momentum-resolved photoemission spectroscopy over a spectral range of 23.6-45.5 eV with sub-100 fs time resolution. Three-dimensional (3D) Fermi surface mapping is demonstrated on graphene-covered Ir(111) with energy and momentum resolutions of ≲100 meV and ≲0.1 Å-1, respectively. The tabletop experiment sets the stage for measuring the kz-dependent ultrafast dynamics of 3D electronic structure, including band structure, Fermi surface, and carrier dynamics in 3D materials as well as 3D orbital dynamics in molecular layers.
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Affiliation(s)
- Michael Heber
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Nils Wind
- Institut für Experimental Physik, Universität Hamburg, 22761 Hamburg, Germany
| | | | | | - Tiberiu Arion
- Centre for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Friedrich Roth
- Institute of Experimental Physics, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Wolfgang Eberhardt
- Centre for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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4
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Li S, Zhou L, Frauenheim T, He J. Light-Controlled Ultrafast Magnetic State Transition in Antiferromagnetic-Ferromagnetic van der Waals Heterostructures. J Phys Chem Lett 2022; 13:6223-6229. [PMID: 35770897 DOI: 10.1021/acs.jpclett.2c01476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Manipulating spin in antiferromagnetic (AFM) materials has great potential in AFM opto-spintronics. Laser pulses can induce a transient ferromagnetic (FM) state in AFM metallic systems but have never been proven in two-dimensional (2D) AFM semiconductors and related van der Waals (vdW) heterostructures. Herein, using 2D vdW heterostructures of FM MnS2 and AFM MXenes as prototypes, we investigated optically induced interlayer spin transfer dynamics based on real-time time-dependent density functional theory. We observed that laser pulses induce significant spin injection and interfacial atom-mediated spin transfer from MnS2 to Cr2CCl2. In particular, we first demonstrated the transient FM state in semiconducting AFM-FM heterostructures during photoexcited processes. The proximity magnetism breaks the magnetic symmetry of Cr2CCl2 in heterostructures. Our results provide a microscopic understanding of optically controlled interlayer spin dynamics in 2D magnetic heterostructures and open a new way to manipulate magnetic order in 2D materials for ultrafast opto-spintronics.
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Affiliation(s)
- Shuo Li
- Institute for Advanced Study, Chengdu University, Chengdu 610100, P. R. China
- Beijing Computational Science Research Center, Beijing 100193, P. R. China
| | - Liujiang Zhou
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Thomas Frauenheim
- Beijing Computational Science Research Center, Beijing 100193, P. R. China
- Bremen Center for Computational Materials Science, University of Bremen, Bremen 28359, Germany
- Shenzhen JL Computational Science and Applied Research Institute, Shenzhen 518110, P. R. China
| | - Junjie He
- Bremen Center for Computational Materials Science, University of Bremen, Bremen 28359, Germany
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Prague 12843, Czechia
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5
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Subpicosecond metamagnetic phase transition in FeRh driven by non-equilibrium electron dynamics. Nat Commun 2021; 12:5088. [PMID: 34429414 PMCID: PMC8384879 DOI: 10.1038/s41467-021-25347-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 07/22/2021] [Indexed: 11/11/2022] Open
Abstract
Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350 ± 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer. In FeRh, it is possible to optically drive a phase transition between ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering. Here, using a combination of photoelectron spectroscopy and ab-initio calculations, the authors demonstrate the existence of a transient intermediate phase, explaining the delayed appearance of the FM phase.
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6
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Golias E, Kumberg I, Gelen I, Thakur S, Gördes J, Hosseinifar R, Guillet Q, Dewhurst JK, Sharma S, Schüßler-Langeheine C, Pontius N, Kuch W. Ultrafast Optically Induced Ferromagnetic State in an Elemental Antiferromagnet. PHYSICAL REVIEW LETTERS 2021; 126:107202. [PMID: 33784145 DOI: 10.1103/physrevlett.126.107202] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 01/15/2021] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
We present evidence for an ultrafast optically induced ferromagnetic alignment of antiferromagnetic Mn in Co/Mn multilayers. We observe the transient ferromagnetic signal at the arrival of the pump pulse at the Mn L_{3} resonance using x-ray magnetic circular dichroism in reflectivity. The timescale of the effect is comparable to the duration of the excitation and occurs before the magnetization in Co is quenched. Theoretical calculations point to the imbalanced population of Mn unoccupied states caused by the Co interface for the emergence of this transient ferromagnetic state.
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Affiliation(s)
- E Golias
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - I Kumberg
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - I Gelen
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - S Thakur
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - J Gördes
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - R Hosseinifar
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Q Guillet
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - J K Dewhurst
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany
| | - S Sharma
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489 Berlin, Germany
| | - C Schüßler-Langeheine
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein Straße 15, 12489 Berlin, Germany
| | - N Pontius
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein Straße 15, 12489 Berlin, Germany
| | - W Kuch
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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7
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Eschenlohr A. Spin dynamics at interfaces on femtosecond timescales. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:013001. [PMID: 33034305 DOI: 10.1088/1361-648x/abb519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The excitation of magnetically ordered materials with ultrashort laser pulses results in magnetization dynamics on femto- to picosecond timescales. These non-equilibrium spin dynamics have emerged as a rapidly developing research field in recent years. Unraveling the fundamental microscopic processes in the interaction of ultrashort optical pulses with the charge, spin, orbital, and lattice degrees of freedom in magnetic materials shows the potential for controlling spin dynamics on their intrinsic timescales and thereby bring spintronics applications into the femtosecond range. In particular, femtosecond spin currents offer fascinating new possibilities to manipulate magnetization in an ultrafast and non-local manner, via spin injection and spin transfer torque at the interfaces of ferromagnetic layered structures. This topical review covers recent progress on spin dynamics at interfaces on femtosecond time scales. The development of the field of ultrafast spin dynamics in ferromagnetic heterostructures will be reviewed, starting from spin currents propagating on nanometer length scales through layered structures before focusing on femtosecond spin transfer at interfaces. The properties of these ultrafast spin-dependent charge currents will be discussed, as well as the materials dependence of femtosecond spin injection, the role of the interface properties, and competing microscopic processes leading to a loss of spin polarization on sub-picosecond timescales.
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Affiliation(s)
- A Eschenlohr
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
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8
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Time-Resolved XUV Absorption Spectroscopy and Magnetic Circular Dichroism at the Ni M2,3-Edges. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app11010325] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ultrashort optical pulses can trigger a variety of non-equilibrium processes in magnetic thin films affecting electrons and spins on femtosecond timescales. In order to probe the charge and magnetic degrees of freedom simultaneously, we developed an X-ray streaking technique that has the advantage of providing a jitter-free picture of absorption cross-section changes. In this paper, we present an experiment based on this approach, which we performed using five photon probing energies at the Ni M2,3-edges. This allowed us to retrieve the absorption and magnetic circular dichroism time traces, yielding detailed information on transient modifications of electron and spin populations close to the Fermi level. Our findings suggest that the observed absorption and magnetic circular dichroism dynamics both depend on the extreme ultraviolet (XUV) probing wavelength, and can be described, at least qualitatively, by assuming ultrafast energy shifts of the electronic and magnetic elemental absorption resonances, as reported in recent work. However, our analysis also hints at more complex changes, highlighting the need for further experimental and theoretical studies in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.
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9
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Bühlmann K, Saerens G, Vaterlaus A, Acremann Y. Detection of femtosecond spin voltage pulses in a thin iron film. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:065101. [PMID: 33195734 PMCID: PMC7647624 DOI: 10.1063/4.0000037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
We present experimental evidence of a spin voltage-a difference between the chemical potentials of the two spin directions-in a thin iron film based on spin- and time-resolved photoemission spectroscopy. This voltage is the driving force for a spin current during the ultrafast demagnetization of the sample. The observed magnitude is on the order of 50 mV, a value that is quite consistent with predictions based on particle conservation and persists for approximately 100 fs.
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Affiliation(s)
| | | | | | - Y. Acremann
- Author to whom correspondence should be addressed:
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10
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Rösner B, Vodungbo B, Chardonnet V, Döring F, Guzenko VA, Hennes M, Kleibert A, Lebugle M, Lüning J, Mahne N, Merhe A, Naumenko D, Nikolov IP, Lopez-Quintas I, Pedersoli E, Ribič PR, Savchenko T, Watts B, Zangrando M, Capotondi F, David C, Jal E. Simultaneous two-color snapshot view on ultrafast charge and spin dynamics in a Fe-Cu-Ni tri-layer. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:054302. [PMID: 32984434 PMCID: PMC7511239 DOI: 10.1063/4.0000033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
Ultrafast phenomena on a femtosecond timescale are commonly examined by pump-probe experiments. This implies multiple measurements, where the sample under investigation is pumped with a short light pulse and then probed with a second pulse at various time delays to follow its dynamics. Recently, the principle of streaking extreme ultraviolet (XUV) pulses in the temporal domain has enabled recording the dynamics of a system within a single pulse. However, separate pump-probe experiments at different absorption edges still lack a unified timing, when comparing the dynamics in complex systems. Here, we report on an experiment using a dedicated optical element and the two-color emission of the FERMI XUV free-electron laser to follow the charge and spin dynamics in composite materials at two distinct absorption edges, simultaneously. The sample, consisting of ferromagnetic Fe and Ni layers, separated by a Cu layer, is pumped by an infrared laser and probed by a two-color XUV pulse with photon energies tuned to the M-shell resonances of these two transition metals. The experimental geometry intrinsically avoids any timing uncertainty between the two elements and unambiguously reveals an approximately 100 fs delay of the magnetic response with respect to the electronic excitation for both Fe and Ni. This delay shows that the electronic and spin degrees of freedom are decoupled during the demagnetization process. We furthermore observe that the electronic dynamics of Ni and Fe show pronounced differences when probed at their resonance, while the demagnetization dynamics are similar. These observations underline the importance of simultaneous investigation of the temporal response of both charge and spin in multi-component materials. In a more general scenario, the experimental approach can be extended to continuous energy ranges, promising the development of jitter-free transient absorption spectroscopy in the XUV and soft X-ray regimes.
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Affiliation(s)
| | - Boris Vodungbo
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
| | - Valentin Chardonnet
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
| | | | | | - Marcel Hennes
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
| | | | | | - Jan Lüning
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
| | - Nicola Mahne
- IOM-CNR, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | - Aladine Merhe
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
| | - Denys Naumenko
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | - Ivaylo P. Nikolov
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | - Ignacio Lopez-Quintas
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | - Emanuele Pedersoli
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | | | | | | | | | - Flavio Capotondi
- Elettra-Sincrotrone Trieste, Strada Statale 14-km 163,5, Basovizza, Trieste 34149, Italy
| | | | - Emmanuelle Jal
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique – Matière et Rayonnement, LCPMR, Paris 75005, France
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11
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Detection of femtosecond spin injection into a thin gold layer by time and spin resolved photoemission. Sci Rep 2020; 10:12632. [PMID: 32724122 PMCID: PMC7387461 DOI: 10.1038/s41598-020-69477-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/13/2020] [Indexed: 11/14/2022] Open
Abstract
The ultrafast demagnetization effect allows for the generation of femtosecond spin current pulses, which is expected to extend the fields of spin transport and spintronics to the femtosecond time domain. Thus far, directly observing the spin polarization induced by spin injection on the femtosecond time scale has not been possible. Herein, we present time- and spin-resolved photoemission results of spin injection from a laser-excited ferromagnet into a thin gold layer. The injected spin polarization is aligned along the magnetization direction of the underlying ferromagnet. Its decay time depends on the thickness of the gold layer, indicating that transport as well as storage of spins are relevant. This capacitive aspect of spin transport may limit the speed of future spintronic devices.
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12
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Bühlmann K, Gort R, Fognini A, Däster S, Holenstein S, Hartmann N, Zemp Y, Salvatella G, Michlmayr TU, Bähler T, Kutnyakhov D, Medjanik K, Schönhense G, Vaterlaus A, Acremann Y. Compact setup for spin-, time-, and angle-resolved photoemission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063001. [PMID: 32611013 DOI: 10.1063/5.0004861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/16/2020] [Indexed: 06/11/2023]
Abstract
We present a compact setup for spin-, time-, and angle-resolved photoemission spectroscopy. A 10 kHz titanium sapphire laser system delivers pulses of 20 fs duration, which drive a high harmonic generation-based source for ultraviolet photons at 21 eV for photoemission. The same laser also excites the sample for pump-probe experiments. Emitted electrons pass through a hemispherical energy analyzer and a spin-filtering element. The latter is based on spin-polarized low-energy electron diffraction on an Au-passivated iridium crystal. The performance of the measurement system is discussed in terms of the resolution and efficiency of the spin filter, which are higher than those for Mott-based techniques.
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Affiliation(s)
- K Bühlmann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - R Gort
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - A Fognini
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - S Däster
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - S Holenstein
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - N Hartmann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Y Zemp
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - G Salvatella
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - T U Michlmayr
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - T Bähler
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - D Kutnyakhov
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - K Medjanik
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - G Schönhense
- Institute of Physics, Johannes Gutenberg University of Mainz, 55128 Mainz, Germany
| | - A Vaterlaus
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Y Acremann
- Laboratory for Solid State Physics, ETH Zurich, 8093 Zurich, Switzerland
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13
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Keunecke M, Möller C, Schmitt D, Nolte H, Jansen GSM, Reutzel M, Gutberlet M, Halasi G, Steil D, Steil S, Mathias S. Time-resolved momentum microscopy with a 1 MHz high-harmonic extreme ultraviolet beamline. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063905. [PMID: 32611056 DOI: 10.1063/5.0006531] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Recent progress in laser-based high-repetition rate extreme ultraviolet (EUV) light sources and multidimensional photoelectron spectroscopy enables the build-up of a new generation of time-resolved photoemission experiments. Here, we present a setup for time-resolved momentum microscopy driven by a 1 MHz fs EUV table-top light source optimized for the generation of 26.5 eV photons. The setup provides simultaneous access to the temporal evolution of the photoelectron's kinetic energy and in-plane momentum. We discuss opportunities and limitations of our new experiment based on a series of static and time-resolved measurements on graphene.
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Affiliation(s)
- Marius Keunecke
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Christina Möller
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - David Schmitt
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hendrik Nolte
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - G S Matthijs Jansen
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marcel Reutzel
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marie Gutberlet
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Gyula Halasi
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Daniel Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sabine Steil
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Stefan Mathias
- I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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14
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Willems F, von Korff Schmising C, Strüber C, Schick D, Engel DW, Dewhurst JK, Elliott P, Sharma S, Eisebitt S. Optical inter-site spin transfer probed by energy and spin-resolved transient absorption spectroscopy. Nat Commun 2020; 11:871. [PMID: 32054855 PMCID: PMC7018696 DOI: 10.1038/s41467-020-14691-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 01/27/2020] [Indexed: 11/09/2022] Open
Abstract
Optically driven spin transport is the fastest and most efficient process to manipulate macroscopic magnetization as it does not rely on secondary mechanisms to dissipate angular momentum. In the present work, we show that such an optical inter-site spin transfer (OISTR) from Pt to Co emerges as a dominant mechanism governing the ultrafast magnetization dynamics of a CoPt alloy. To demonstrate this, we perform a joint theoretical and experimental investigation to determine the transient changes of the helicity dependent absorption in the extreme ultraviolet spectral range. We show that the helicity dependent absorption is directly related to changes of the transient spin-split density of states, allowing us to link the origin of OISTR to the available minority states above the Fermi level. This makes OISTR a general phenomenon in optical manipulation of multi-component magnetic systems.
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Affiliation(s)
- Felix Willems
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - Clemens von Korff Schmising
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany.
| | - Christian Strüber
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - Daniel Schick
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - Dieter W Engel
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - J K Dewhurst
- Max-Planck-Institute for Microstructure Physics, Weinberg 2, 06120, Halle (Saale), Germany
| | - Peter Elliott
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - Sangeeta Sharma
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
| | - Stefan Eisebitt
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, 12489, Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623, Berlin, Germany
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15
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Hofherr M, Häuser S, Dewhurst JK, Tengdin P, Sakshath S, Nembach HT, Weber ST, Shaw JM, Silva TJ, Kapteyn HC, Cinchetti M, Rethfeld B, Murnane MM, Steil D, Stadtmüller B, Sharma S, Aeschlimann M, Mathias S. Ultrafast optically induced spin transfer in ferromagnetic alloys. SCIENCE ADVANCES 2020; 6:eaay8717. [PMID: 32010774 PMCID: PMC6968944 DOI: 10.1126/sciadv.aay8717] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 10/09/2019] [Indexed: 05/23/2023]
Abstract
The vision of using light to manipulate electronic and spin excitations in materials on their fundamental time and length scales requires new approaches in experiment and theory to observe and understand these excitations. The ultimate speed limit for all-optical manipulation requires control schemes for which the electronic or magnetic subsystems of the materials are coherently manipulated on the time scale of the laser excitation pulse. In our work, we provide experimental evidence of such a direct, ultrafast, and coherent spin transfer between two magnetic subsystems of an alloy of Fe and Ni. Our experimental findings are fully supported by time-dependent density functional theory simulations and, hence, suggest the possibility of coherently controlling spin dynamics on subfemtosecond time scales, i.e., the birth of the research area of attomagnetism.
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Affiliation(s)
- M. Hofherr
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - S. Häuser
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - J. K. Dewhurst
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - P. Tengdin
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - S. Sakshath
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - H. T. Nembach
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - S. T. Weber
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - J. M. Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - T. J. Silva
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - H. C. Kapteyn
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - M. Cinchetti
- Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - B. Rethfeld
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - M. M. Murnane
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - D. Steil
- Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - B. Stadtmüller
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
- Graduate School of Excellence Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - S. Sharma
- Max Born Institute for Nonlinear Optics, Max-Born-Strasse 2A, 12489 Berlin, Germany
| | - M. Aeschlimann
- Technische Universität Kaiserslautern und Landesforschungszentrum OPTIMAS, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - S. Mathias
- Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Corresponding author.
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16
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Tengdin P, Gentry C, Blonsky A, Zusin D, Gerrity M, Hellbrück L, Hofherr M, Shaw J, Kvashnin Y, Delczeg-Czirjak EK, Arora M, Nembach H, Silva TJ, Mathias S, Aeschlimann M, Kapteyn HC, Thonig D, Koumpouras K, Eriksson O, Murnane MM. Direct light-induced spin transfer between different elements in a spintronic Heusler material via femtosecond laser excitation. SCIENCE ADVANCES 2020; 6:eaaz1100. [PMID: 32010777 PMCID: PMC6968936 DOI: 10.1126/sciadv.aaz1100] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 11/26/2019] [Indexed: 05/23/2023]
Abstract
Heusler compounds are exciting materials for future spintronics applications because they display a wide range of tunable electronic and magnetic interactions. Here, we use a femtosecond laser to directly transfer spin polarization from one element to another in a half-metallic Heusler material, Co2MnGe. This spin transfer initiates as soon as light is incident on the material, demonstrating spatial transfer of angular momentum between neighboring atomic sites on time scales < 10 fs. Using ultrafast high harmonic pulses to simultaneously and independently probe the magnetic state of two elements during laser excitation, we find that the magnetization of Co is enhanced, while that of Mn rapidly quenches. Density functional theory calculations show that the optical excitation directly transfers spin from one magnetic sublattice to another through preferred spin-polarized excitation pathways. This direct manipulation of spins via light provides a path toward spintronic devices that can operate on few-femtosecond or faster time scales.
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Affiliation(s)
- Phoebe Tengdin
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Christian Gentry
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Adam Blonsky
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Dmitriy Zusin
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Michael Gerrity
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Lukas Hellbrück
- Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Moritz Hofherr
- Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Justin Shaw
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Yaroslav Kvashnin
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
| | | | - Monika Arora
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Hans Nembach
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Tom J. Silva
- Quantum Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Stefan Mathias
- Georg-August-Universität Göttingen, I. Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Martin Aeschlimann
- Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger Strasse 46, 67663 Kaiserslautern, Germany
| | - Henry C. Kapteyn
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
| | - Danny Thonig
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
- School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | | | - Olle Eriksson
- Department of Physics and Astronomy, University Uppsala, S-75120 Uppsala, Sweden
- School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | - Margaret M. Murnane
- Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA
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17
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Femtosecond X-ray induced changes of the electronic and magnetic response of solids from electron redistribution. Nat Commun 2019; 10:5289. [PMID: 31754109 PMCID: PMC6872582 DOI: 10.1038/s41467-019-13272-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 10/24/2019] [Indexed: 11/08/2022] Open
Abstract
Resonant X-ray absorption, where an X-ray photon excites a core electron into an unoccupied valence state, is an essential process in many standard X-ray spectroscopies. With increasing X-ray intensity, the X-ray absorption strength is expected to become nonlinear. Here, we report the onset of such a nonlinearity in the resonant X-ray absorption of magnetic Co/Pd multilayers near the Co L[Formula: see text] edge. The nonlinearity is directly observed through the change of the absorption spectrum, which is modified in less than 40 fs within 2 eV of its threshold. This is interpreted as a redistribution of valence electrons near the Fermi level. For our magnetic sample this also involves mixing of majority and minority spins, due to sample demagnetization. Our findings reveal that nonlinear X-ray responses of materials may already occur at relatively low intensities, where the macroscopic sample is not destroyed, providing insight into ultrafast charge and spin dynamics.
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