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Hübner W, Lefkidis G, Zhang GP. All-optical spin switching on an ultrafast time scale. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:403001. [PMID: 38917839 DOI: 10.1088/1361-648x/ad5bae] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 06/25/2024] [Indexed: 06/27/2024]
Abstract
Information technology revolution demands bigger and faster magnetic storage. All-optical spin switching (AOS) may offer a solution, where an ultrafast laser pulse alone can switch magnetization from one direction to another faithfully within 1-10 ps, free of a magnetic field. There are two types of switching: One is the helicity-dependent all-optical spin switching (HD-AOS) and the other the helicity-independent all-optical spin switching (HID-AOS). In a few alloys, one single laser pulse, with sufficient fluence, can switch spin, but the majority of magnetic materials requires multiple pulses. Both material-specific and laser-specific properties strongly affect the switching process. However, the underlying mechanism is still under debate. As the entire research field moves toward applications, it is very appropriate to review what has been achieved in the last decade. This review covers some of the major experimental and theoretical developments within the last decade, and serves as an introduction to the uninitiated reader in this field and a summary for the seasoned researchers.
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Affiliation(s)
- Wolfgang Hübner
- Department of Physics, Rheinland-Pfälzische Technische Universität, Kaiserslautern-Landau, 67653 Kaiserslautern, Germany
| | - Georgios Lefkidis
- Department of Physics, Rheinland-Pfälzische Technische Universität, Kaiserslautern-Landau, 67653 Kaiserslautern, Germany
| | - G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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2
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Johnsen PC, Ryan SA, Gentry C, Grafov A, Kapteyn H, Murnane M. A beamline for ultrafast extreme ultraviolet magneto-optical spectroscopy in reflection near the shot noise limit. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:033001. [PMID: 37012828 DOI: 10.1063/5.0127119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/30/2023] [Indexed: 06/19/2023]
Abstract
High harmonic generation (HHG) makes it possible to measure spin and charge dynamics in materials on femtosecond to attosecond timescales. However, the extreme nonlinear nature of the high harmonic process means that intensity fluctuations can limit measurement sensitivity. Here we present a noise-canceled, tabletop high harmonic beamline for time-resolved reflection mode spectroscopy of magnetic materials. We use a reference spectrometer to independently normalize the intensity fluctuations of each harmonic order and eliminate long term drift, allowing us to make spectroscopic measurements near the shot noise limit. These improvements allow us to significantly reduce the integration time required for high signal-to-noise (SNR) measurements of element-specific spin dynamics. Looking forward, improvements in the HHG flux, optical coatings, and grating design can further reduce the acquisition time for high SNR measurements by 1-2 orders of magnitude, enabling dramatically improved sensitivity to spin, charge, and phonon dynamics in magnetic materials.
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Affiliation(s)
- Peter C Johnsen
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
| | - Sinéad A Ryan
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
| | - Christian Gentry
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
| | - Anya Grafov
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
| | - Henry Kapteyn
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
| | - Margaret Murnane
- Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440, USA
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3
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Observation of spin-glass-like characteristics in ferrimagnetic TbCo through energy-level-selective approach. Nat Commun 2022; 13:5530. [PMID: 36130955 PMCID: PMC9492764 DOI: 10.1038/s41467-022-33195-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 09/07/2022] [Indexed: 11/12/2022] Open
Abstract
Rare earth (RE)–transition metal (TM) ferrimagnetic alloys are gaining increasing attention because of their potential use in the field of antiferromagnetic spintronics. The moment from RE sub-lattice primarily originates from the 4f-electrons located far below the Fermi level (EF), and the moment from TM sub-lattice arises from the 3d-electrons across the EF. Therefore, the individual magnetic moment configurations at different energy levels must be explored to clarify the microscopic mechanism of antiferromagnetic spin dynamics. Considering these issues, here we investigate the energy-level-selective magnetic moment configuration in ferrimagnetic TbCo alloy. We reveal that magnetic moments at deeper energy levels are more easily altered by the external magnetic field than those near the EF. More importantly, we find that the magnetic moments at deeper energy levels exhibit a spin-glass-like characteristics such as slow dynamics and magnetic moment freezing whereas those at EF do not. These unique energy-level-dependent characteristics of RE-TM ferrimagnet may provide a better understanding of ferrimagnet, which could be useful in spintronic applications as well as in spin-glass studies. In a ferrimagnet, there are two magnetic sublattices coupled antiferromagnetically. The dynamics of the two magnetic sublattices isn’t well understood, as the magnetic moments for each reside at different energy levels. Here, Park et al show that the magnetic moments at deeper energy levels show spin-glass like characteristics.
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Pancaldi M, Strüber C, Friedrich B, Pedersoli E, De Angelis D, Nikolov IP, Manfredda M, Foglia L, Yulin S, Spezzani C, Sacchi M, Eisebitt S, von Korff Schmising C, Capotondi F. The COMIX polarimeter: a compact device for XUV polarization analysis. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:969-977. [PMID: 35787562 PMCID: PMC9255573 DOI: 10.1107/s1600577522004027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
We report on the characterization of a novel extreme-ultraviolet polarimeter based on conical mirrors to simultaneously detect all the components of the electric field vector for extreme-ultraviolet radiation in the 45-90 eV energy range. The device has been characterized using a variable polarization source at the Elettra synchrotron, showing good performance in the ability to determine the radiation polarization. Furthermore, as a possible application of the device, Faraday spectroscopy and time-resolved experiments have been performed at the Fe M2,3-edge on an FeGd ferrimagnetic thin film using the FERMI free-electron laser source. The instrument is shown to be able to detect the small angular variation induced by an optical external stimulus on the polarization state of the light after interaction with magnetic thin film, making the device an appealing tool for magnetization dynamics research.
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Affiliation(s)
| | - Christian Strüber
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Bertram Friedrich
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | | | | | | | | | - Laura Foglia
- Elettra-Sincrotrone Trieste SCpA, 34149 Basovizza, Italy
| | - Sergiy Yulin
- Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Albert-Einstein-Straße 7, 07745 Jena, Germany
| | - Carlo Spezzani
- Elettra-Sincrotrone Trieste SCpA, 34149 Basovizza, Italy
| | - Maurizio Sacchi
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Stefan Eisebitt
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany
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5
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Sutcliffe J, Johansson JO. A femtosecond magnetic circular dichroism spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:113001. [PMID: 34852523 DOI: 10.1063/5.0064460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/09/2021] [Indexed: 06/13/2023]
Abstract
We describe the development of a broadband magneto-optical spectrometer with femtosecond temporal resolution. The absorption spectrometer is based on a white-light supercontinuum (∼320 to 750 nm) using shot-to-shot temporal and spectral referencing at 1 kHz. Static and transient absorption spectra using circularly polarized light are collected in a magnetic field. The difference spectra with respect to the external field direction give the static and transient magneto-optical Faraday rotation (magnetic optical rotary dispersion) and ellipticity (magnetic circular dichroism) spectra. An achromatic quarter-wave plate is used, and the impact of the deviation from ideal retardance on the spectra is discussed. Results from solution-based and thin-film samples are used to demonstrate the performance and wide applicability of the instrument. The sensitivities for the static and time-resolved data were found to be 5 and 0.4 mdeg, respectively. The method presents a simple way to measure magneto-optical spectra using a transient absorption spectrometer and an electromagnet.
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Affiliation(s)
- Jake Sutcliffe
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - J Olof Johansson
- School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
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6
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Banerjee C, Teichert N, Siewierska KE, Gercsi Z, Atcheson GYP, Stamenov P, Rode K, Coey JMD, Besbas J. Single pulse all-optical toggle switching of magnetization without gadolinium in the ferrimagnet Mn 2Ru xGa. Nat Commun 2020; 11:4444. [PMID: 32895392 PMCID: PMC7477543 DOI: 10.1038/s41467-020-18340-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/12/2020] [Indexed: 11/19/2022] Open
Abstract
Energy-efficient control of magnetization without the help of a magnetic field is a key goal of spintronics. Purely heat-induced single-pulse all-optical toggle switching has been demonstrated, but so far only in Gd-based amorphous ferrimagnet films. In this work, we demonstrate toggle switching in films of the half-metallic ferrimagnetic Heusler alloys Mn2RuxGa, which have two crystallographically-inequivalent Mn sublattices. Moreover, we observe the switching at room temperature in samples that are immune to external magnetic fields in excess of 1 T, provided they exhibit a compensation point above room temperature. Observation of the effect in compensated ferrimagnets without Gd challenges our understanding of all-optical switching. The dynamic behavior indicates that Mn2RuxGa switches in 2 ps or less. Our findings widen the basis for fast optical switching of magnetization and break new ground for engineered materials that can be used for nonvolatile ultrafast switches using ultrashort pulses of light.
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Affiliation(s)
- C Banerjee
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - N Teichert
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - K E Siewierska
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Z Gercsi
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - G Y P Atcheson
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - P Stamenov
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - K Rode
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - J M D Coey
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - J Besbas
- CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2, Ireland.
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7
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Gomez MJ, Liu K, Lee JG, Wilson RB. High sensitivity pump-probe measurements of magnetic, thermal, and acoustic phenomena with a spectrally tunable oscillator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:023905. [PMID: 32113424 DOI: 10.1063/1.5126121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
We describe an optical pump/probe system for sensitive measurements of time-resolved optical measurements of material dynamics. The instrument design is optimized for time-resolved magneto-optic Kerr effect (TR-MOKE) measurements of dynamics in magnetic materials. The system also allows for time-domain thermoreflectance (TDTR) measurements of thermal transport properties and picosecond acoustic measurements of film thickness and/or elastic constants. The system has several advantages over the conventional designs for TR-MOKE and/or TDTR systems. Measurements of pump-induced changes to the probe beam intensity are shot-noise limited. The system's design allows for MOKE and/or thermoreflectance measurements of both sides of a sample. Pumping and probing the sample on opposite sides allows nanoscale flash diffusivity measurements of transport properties. The wavelengths of the pump and probe beams are straightforward to tune between 350-525 nm and 690-1050 nm. A tunable wavelength allows for optical resonances in a wide array of materials to be excited and/or probed. Finally, the setup is calibrated to allow for the real and imaginary components of Kerr signals to be separately quantified.
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Affiliation(s)
- Michael J Gomez
- Materials Science and Engineering, University of California, Riverside, California 92521, USA
| | - Kexin Liu
- Mechanical Engineering, University of California, Riverside, California 92521, USA
| | - Jonathan G Lee
- Mechanical Engineering, University of California, Riverside, California 92521, USA
| | - Richard B Wilson
- Materials Science and Engineering, University of California, Riverside, California 92521, USA
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Liao J, Vallobra P, O'Brien L, Atxitia U, Raposo V, Petit D, Vemulkar T, Malinowski G, Hehn M, Martínez E, Mangin S, Cowburn RP. Controlling All-Optical Helicity-Dependent Switching in Engineered Rare-Earth Free Synthetic Ferrimagnets. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901876. [PMID: 31871864 PMCID: PMC6918116 DOI: 10.1002/advs.201901876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/25/2019] [Indexed: 06/10/2023]
Abstract
All-optical helicity-dependent switching in ferromagnetic layers has revealed an unprecedented route to manipulate magnetic configurations by circularly polarized femtosecond laser pulses. In this work, rare-earth free synthetic ferrimagnetic heterostructures made from two antiferromagnetically exchange coupled ferromagnetic layers are studied. Experimental results, supported by numerical simulations, show that the designed structures enable all-optical switching which is controlled, not only by light helicity, but also by the relative Curie temperature of each ferromagnetic layer. Indeed, through the antiferromagnetic exchange coupling, the layer with the larger Curie temperature determines the final orientation of the other layer and so the synthetic ferrimagnet. For similar Curie temperatures, helicity-independent back switching is observed and the final magnetic configuration is solely determined by the initial magnetic state. This demonstration of electrically-detected, optical control of engineered rare-earth free heterostructures opens a novel route toward practical opto-spintronics.
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Affiliation(s)
- Jung‐Wei Liao
- Cavendish LaboratoryUniversity of CambridgeJ J Thomson AvenueCambridgeCB3 0HEUK
| | - Pierre Vallobra
- Institute Jean LamourUMR CNRS 7198Universite de Lorraine2 allée André Guinier‐BP 5084054011NancyFrance
| | - Liam O'Brien
- Department of PhysicsUniversity of LiverpoolLiverpoolL69 7ZEUK
| | - Unai Atxitia
- Department of PhysicsFreie Universität BerlinArnimalle 1414195BerlinGermany
| | - Victor Raposo
- Department of Applied Physics of the Faculty of ScienceUniversity of Salamanca37008SalamancaSpain
| | - Dorothée Petit
- Cavendish LaboratoryUniversity of CambridgeJ J Thomson AvenueCambridgeCB3 0HEUK
| | - Tarun Vemulkar
- Cavendish LaboratoryUniversity of CambridgeJ J Thomson AvenueCambridgeCB3 0HEUK
| | - Gregory Malinowski
- Institute Jean LamourUMR CNRS 7198Universite de Lorraine2 allée André Guinier‐BP 5084054011NancyFrance
| | - Michel Hehn
- Institute Jean LamourUMR CNRS 7198Universite de Lorraine2 allée André Guinier‐BP 5084054011NancyFrance
| | - Eduardo Martínez
- Department of Applied Physics of the Faculty of ScienceUniversity of Salamanca37008SalamancaSpain
| | - Stéphane Mangin
- Institute Jean LamourUMR CNRS 7198Universite de Lorraine2 allée André Guinier‐BP 5084054011NancyFrance
| | - Russell P. Cowburn
- Cavendish LaboratoryUniversity of CambridgeJ J Thomson AvenueCambridgeCB3 0HEUK
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9
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Zeuschner SP, Parpiiev T, Pezeril T, Hillion A, Dumesnil K, Anane A, Pudell J, Willig L, Rössle M, Herzog M, von Reppert A, Bargheer M. Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:024302. [PMID: 31041360 PMCID: PMC6447272 DOI: 10.1063/1.5084140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 02/26/2019] [Indexed: 05/06/2023]
Abstract
We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe2/Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe2 surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO2 glass capping layer covers the excited TbFe2 layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.
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Affiliation(s)
| | - T Parpiiev
- Institut des Molécules et Matériaux du Mans (UMR CNRS 6283), Université du Maine, 72085 Le Mans Cedex, France
| | - T Pezeril
- Institut des Molécules et Matériaux du Mans (UMR CNRS 6283), Université du Maine, 72085 Le Mans Cedex, France
| | - A Hillion
- Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, 54000 Nancy, France
| | - K Dumesnil
- Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, 54000 Nancy, France
| | - A Anane
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - J Pudell
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - L Willig
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - M Rössle
- Helmholtz-Zentrum Berlin, Wilhelm-Conrad-Röntgen-Campus, BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - M Herzog
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
| | - A von Reppert
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam, Germany
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10
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Malvestuto M, Ciprian R, Caretta A, Casarin B, Parmigiani F. Ultrafast magnetodynamics with free-electron lasers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:053002. [PMID: 29315080 DOI: 10.1088/1361-648x/aaa211] [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
The study of ultrafast magnetodynamics has entered a new era thanks to the groundbreaking technological advances in free-electron laser (FEL) light sources. The advent of these light sources has made possible unprecedented experimental schemes for time-resolved x-ray magneto-optic spectroscopies, which are now paving the road for exploring the ultimate limits of out-of-equilibrium magnetic phenomena. In particular, these studies will provide insights into elementary mechanisms governing spin and orbital dynamics, therefore contributing to the development of ultrafast devices for relevant magnetic technologies. This topical review focuses on recent advancement in the study of non-equilibrium magnetic phenomena from the perspective of time-resolved extreme ultra violet (EUV) and soft x-ray spectroscopies at FELs with highlights of some important experimental results.
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Affiliation(s)
- Marco Malvestuto
- Elettra-Sincrotrone Trieste S.C.p.A. Strada Statale 14-km 163.5 in AREA Science Park 34149 Basovizza, Trieste, Italy
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11
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Measurement of the Resonant Magneto-Optical Kerr Effect Using a Free Electron Laser. APPLIED SCIENCES-BASEL 2017. [DOI: 10.3390/app7070662] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Koene B, Deb M, Popova E, Keller N, Rasing T, Kirilyuk A. Spectrally resolved optical probing of laser induced magnetization dynamics in bismuth iron garnet. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:276002. [PMID: 27213266 DOI: 10.1088/0953-8984/28/27/276002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The spectrally resolved magnetization dynamics in bismuth iron garnet shows a fluence dependent light induced modification of the magneto-optical Faraday spectrum. It is demonstrated that the relative contributions from the tetrahedral and octahedral iron sites to the Faraday spectrum change due to the impact of the pump pulse. This change explains the observed deviation from a linear dependence of the amplitude of the oscillations on the fluence, as expected for the inverse Faraday effect.
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Affiliation(s)
- Benny Koene
- Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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13
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Chakraborty S, Vijay A. Effective Hamiltonians for correlated narrow energy band systems and magnetic insulators: Role of spin-orbit interactions in metal-insulator transitions and magnetic phase transitions. J Chem Phys 2016; 144:144107. [PMID: 27083708 DOI: 10.1063/1.4945705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Using a second-quantized many-electron Hamiltonian, we obtain (a) an effective Hamiltonian suitable for materials whose electronic properties are governed by a set of strongly correlated bands in a narrow energy range and (b) an effective spin-only Hamiltonian for magnetic materials. The present Hamiltonians faithfully include phonon and spin-related interactions as well as the external fields to study the electromagnetic response properties of complex materials and they, in appropriate limits, reduce to the model Hamiltonians due to Hubbard and Heisenberg. With the Hamiltonian for narrow-band strongly correlated materials, we show that the spin-orbit interaction provides a mechanism for metal-insulator transition, which is distinct from the Mott-Hubbard (driven by the electron correlation) and the Anderson mechanism (driven by the disorder). Next, with the spin-only Hamiltonian, we demonstrate the spin-orbit interaction to be a reason for the existence of antiferromagnetic phase in materials which are characterized by a positive isotropic spin-exchange energy. This is distinct from the Néel-VanVleck-Anderson paradigm which posits a negative spin-exchange for the existence of antiferromagnetism. We also find that the Néel temperature increases as the absolute value of the spin-orbit coupling increases.
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Affiliation(s)
- Subrata Chakraborty
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
| | - Amrendra Vijay
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India
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14
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Frietsch B, Bowlan J, Carley R, Teichmann M, Wienholdt S, Hinzke D, Nowak U, Carva K, Oppeneer PM, Weinelt M. Disparate ultrafast dynamics of itinerant and localized magnetic moments in gadolinium metal. Nat Commun 2015; 6:8262. [PMID: 26355196 PMCID: PMC4579838 DOI: 10.1038/ncomms9262] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 08/04/2015] [Indexed: 01/26/2023] Open
Abstract
The Heisenberg–Dirac intra-atomic exchange coupling is responsible for the formation of the atomic spin moment and thus the strongest interaction in magnetism. Therefore, it is generally assumed that intra-atomic exchange leads to a quasi-instantaneous aligning process in the magnetic moment dynamics of spins in separate, on-site atomic orbitals. Following ultrashort optical excitation of gadolinium metal, we concurrently record in photoemission the 4f magnetic linear dichroism and 5d exchange splitting. Their dynamics differ by one order of magnitude, with decay constants of 14 versus 0.8 ps, respectively. Spin dynamics simulations based on an orbital-resolved Heisenberg Hamiltonian combined with first-principles calculations explain the particular dynamics of 5d and 4f spin moments well, and corroborate that the 5d exchange splitting traces closely the 5d spin-moment dynamics. Thus gadolinium shows disparate dynamics of the localized 4f and the itinerant 5d spin moments, demonstrating a breakdown of their intra-atomic exchange alignment on a picosecond timescale. Due the strength of the intra-atomic exchange interaction, it is generally assumed that alignment of spin moments in intra-atomic orbitals is quasi-instantaneous. Here, the authors demonstrate the breakdown of this relation between the 4f and 5d electrons in gadolinium following ultrashort optical excitation.
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Affiliation(s)
- B Frietsch
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.,Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - J Bowlan
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.,Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - R Carley
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.,Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - M Teichmann
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.,Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - S Wienholdt
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - D Hinzke
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - U Nowak
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - K Carva
- Department of Physics and Astronomy, Uppsala University, PO Box 516, 75120 Uppsala, Sweden.,Charles University, Faculty of Mathematics and Physics, DCMP, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - P M Oppeneer
- Department of Physics and Astronomy, Uppsala University, PO Box 516, 75120 Uppsala, Sweden
| | - M Weinelt
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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Yamamoto S, Taguchi M, Someya T, Kubota Y, Ito S, Wadati H, Fujisawa M, Capotondi F, Pedersoli E, Manfredda M, Raimondi L, Kiskinova M, Fujii J, Moras P, Tsuyama T, Nakamura T, Kato T, Higashide T, Iwata S, Yamamoto S, Shin S, Matsuda I. Ultrafast spin-switching of a ferrimagnetic alloy at room temperature traced by resonant magneto-optical Kerr effect using a seeded free electron laser. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:083901. [PMID: 26329205 DOI: 10.1063/1.4927828] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ultrafast magnetization reversal of a ferrimagnetic metallic alloy GdFeCo was investigated by time-resolved resonant magneto-optical Kerr effect measurements using a seeded free electron laser. The GdFeCo alloy was pumped by a linearly polarized optical laser pulse, and the following temporal evolution of the magnetization of Fe in GdFeCo was element-selectively traced by a probe free electron laser pulse with a photon energy tuned to the Fe M-edge. The results have been measured using rotating analyzer ellipsometry method and confirmed magnetization switching caused by ultrafast heating.
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Affiliation(s)
- Sh Yamamoto
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - M Taguchi
- Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan
| | - T Someya
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Y Kubota
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - S Ito
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - H Wadati
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - M Fujisawa
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - F Capotondi
- Elettra-Sincrotrone Trieste, SS 14 - km 163.5, I-34149 Basovizza, Trieste, Italy
| | - E Pedersoli
- Elettra-Sincrotrone Trieste, SS 14 - km 163.5, I-34149 Basovizza, Trieste, Italy
| | - M Manfredda
- Elettra-Sincrotrone Trieste, SS 14 - km 163.5, I-34149 Basovizza, Trieste, Italy
| | - L Raimondi
- Elettra-Sincrotrone Trieste, SS 14 - km 163.5, I-34149 Basovizza, Trieste, Italy
| | - M Kiskinova
- Elettra-Sincrotrone Trieste, SS 14 - km 163.5, I-34149 Basovizza, Trieste, Italy
| | - J Fujii
- Laboratorio TASC, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, I-34012 Basovizza, Trieste, Italy
| | - P Moras
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - T Tsuyama
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - T Nakamura
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - T Kato
- Department of Electrical Engineering and Computer Science, Nagoya University, Chikusa, Nagoya 464-8603, Japan
| | - T Higashide
- Department of Electrical Engineering and Computer Science, Nagoya University, Chikusa, Nagoya 464-8603, Japan
| | - S Iwata
- Division of Integrated Research Projects, EcoTopia Science Institute, Nagoya University, Chikusa, Nagoya 464-8603, Japan
| | - S Yamamoto
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - S Shin
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - I Matsuda
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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16
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Mangin S, Gottwald M, Lambert CH, Steil D, Uhlíř V, Pang L, Hehn M, Alebrand S, Cinchetti M, Malinowski G, Fainman Y, Aeschlimann M, Fullerton EE. Engineered materials for all-optical helicity-dependent magnetic switching. NATURE MATERIALS 2014; 13:286-92. [PMID: 24531398 DOI: 10.1038/nmat3864] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 12/13/2013] [Indexed: 05/23/2023]
Abstract
The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order.
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Affiliation(s)
- S Mangin
- 1] Center for Magnetic Recording Research, University of California San Diego La Jolla, California 92093-0401 USA [2] Institut Jean Lamour, UMR CNRS 7198 - Université de Lorraine - boulevard des aiguillettes BP 70239, Vandoeuvre cedex F-54506 France
| | - M Gottwald
- Center for Magnetic Recording Research, University of California San Diego La Jolla, California 92093-0401 USA
| | - C-H Lambert
- 1] Center for Magnetic Recording Research, University of California San Diego La Jolla, California 92093-0401 USA [2] Institut Jean Lamour, UMR CNRS 7198 - Université de Lorraine - boulevard des aiguillettes BP 70239, Vandoeuvre cedex F-54506 France
| | - D Steil
- Department of Physics and Research Center OPTIMAS University of Kaiserslautern Erwin Schroedinger Str. 46 Kaiserslautern D-67663 Germany
| | - V Uhlíř
- Center for Magnetic Recording Research, University of California San Diego La Jolla, California 92093-0401 USA
| | - L Pang
- Department of Electrical and Computer Engineering, University of California San Diego La Jolla, California 92093-0401 USA
| | - M Hehn
- Institut Jean Lamour, UMR CNRS 7198 - Université de Lorraine - boulevard des aiguillettes BP 70239, Vandoeuvre cedex F-54506 France
| | - S Alebrand
- Department of Physics and Research Center OPTIMAS University of Kaiserslautern Erwin Schroedinger Str. 46 Kaiserslautern D-67663 Germany
| | - M Cinchetti
- Department of Physics and Research Center OPTIMAS University of Kaiserslautern Erwin Schroedinger Str. 46 Kaiserslautern D-67663 Germany
| | - G Malinowski
- 1] Institut Jean Lamour, UMR CNRS 7198 - Université de Lorraine - boulevard des aiguillettes BP 70239, Vandoeuvre cedex F-54506 France [2] Laboratoire de Physique des Solides, Université Paris-Sud, CNRS UMR 8502 Orsay 91405 France
| | - Y Fainman
- Department of Electrical and Computer Engineering, University of California San Diego La Jolla, California 92093-0401 USA
| | - M Aeschlimann
- Department of Physics and Research Center OPTIMAS University of Kaiserslautern Erwin Schroedinger Str. 46 Kaiserslautern D-67663 Germany
| | - E E Fullerton
- 1] Center for Magnetic Recording Research, University of California San Diego La Jolla, California 92093-0401 USA [2] Department of Electrical and Computer Engineering, University of California San Diego La Jolla, California 92093-0401 USA
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17
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Two-magnon bound state causes ultrafast thermally induced magnetisation switching. Sci Rep 2013; 3:3262. [PMID: 24253110 PMCID: PMC3834892 DOI: 10.1038/srep03262] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 10/30/2013] [Indexed: 11/08/2022] Open
Abstract
There has been much interest recently in the discovery of thermally induced magnetisation switching using femtosecond laser excitation, where a ferrimagnetic system can be switched deterministically without an applied magnetic field. Experimental results suggest that the reversal occurs due to intrinsic material properties, but so far the microscopic mechanism responsible for reversal has not been identified. Using computational and analytic methods we show that the switching is caused by the excitation of two-magnon bound states, the properties of which are dependent on material factors. This discovery allows us to accurately predict the onset of switching and the identification of this mechanism will allow new classes of materials to be identified or designed for memory devices in the THz regime.
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