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Kong C, Song L, Zhao X, Wang H, Zhao J, Yuan G, Zhang X. Enhancing Magnetic Damping under GaAs Band-Edge Photoexcitation in a Co 2FeAl/ n-GaAs Heterojunction. ACS APPLIED MATERIALS & INTERFACES 2024; 16:17041-17050. [PMID: 38517684 DOI: 10.1021/acsami.4c01858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/24/2024]
Abstract
The ultrafast manipulation of spin in ferromagnet-semiconductor (FM/SC) heterojunctions is a key issue for advancing spintronics, where magnetic damping and interfacial spin transport often define device efficiency. Leveraging selective optical excitation in semiconductors offers a unique approach to spin manipulation in FM/SC heterojunctions. Herein, we investigated the magnetic dynamics of a Co2FeAl/n-GaAs heterojunction using the time-resolved magneto-optical Kerr technique and observed the considerably enhanced magnetic damping of Co2FeAl when GaAs is photoexcited near its band edge. This enhancement is attributed to an enhanced spin-pumping effect facilitated by spin-dependent carrier tunneling and capture within the Co2FeAl layer. Moreover, circularly polarized light excites spin-polarized band-edge photocarriers, further impacting the magnetic damping of Co2FeAl through an additional optical spin-transfer torque on the magnetic moment of Co2FeAl. Our results provide a valuable reference for manipulating spin-pumping and interfacial spin transport in FM/SC heterojunctions, showcasing the advantage of optical control of semiconductor photocarriers for the ultrafast manipulation of magnetic dynamics and interfacial spin transfer.
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Affiliation(s)
- Chongtao Kong
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Lin Song
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xupeng Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guodong Yuan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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2
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Chen Z, Luo JW, Wang LW. Light-induced ultrafast spin transport in multilayer metallic films originates from sp- d spin exchange coupling. SCIENCE ADVANCES 2023; 9:eadi1618. [PMID: 38100591 PMCID: PMC10848703 DOI: 10.1126/sciadv.adi1618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 11/15/2023] [Indexed: 12/17/2023]
Abstract
Ultrafast interaction between the femtosecond laser pulse and the magnetic metal provides an efficient way to manipulate the magnetic states of matter. Numerous experimental advancements have been made on multilayer metallic films in the last two decades. However, the underlying physics remains unclear. Here, relying on an efficient ab initio spin dynamics simulation algorithm, we revealed the physics that can unify the progress in different experiments. We found that light-induced ultrafast spin transport in multilayer metallic films originates from the sp-d spin-exchange interaction, which can induce an ultrafast, large, and pure spin current from ferromagnetic metal to nonmagnetic metal without charge carrier transport. The resulting trends of spin demagnetization and spin flow are consistent with most experiments. It can explain a variety of ultrafast light-spin manipulation experiments with different systems and different pump-probe technologies, covering a wide range of work in this field.
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Affiliation(s)
- Zhanghui Chen
- Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
- Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 50F, Berkeley, CA 94720, USA
- University of Chinese Academy of Sciences, No.1 Yanqihu East Rd, Huairou District, Beijing 101408, China
| | - Jun-Wei Luo
- Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
- University of Chinese Academy of Sciences, No.1 Yanqihu East Rd, Huairou District, Beijing 101408, China
| | - Lin-Wang Wang
- Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
- Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 50F, Berkeley, CA 94720, USA
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Guillemard C, Zhang W, Malinowski G, de Melo C, Gorchon J, Petit-Watelot S, Ghanbaja J, Mangin S, Le Fèvre P, Bertran F, Andrieu S. Engineering Co 2 MnAl x Si 1- x Heusler Compounds as a Model System to Correlate Spin Polarization, Intrinsic Gilbert Damping, and Ultrafast Demagnetization. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1908357. [PMID: 32452576 DOI: 10.1002/adma.201908357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/07/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Engineering of magnetic materials for developing better spintronic applications relies on the control of two key parameters: the spin polarization and the Gilbert damping, responsible for the spin angular momentum dissipation. Both of them are expected to affect the ultrafast magnetization dynamics occurring on the femtosecond timescale. Here, engineered Co2 MnAlx Si1- x Heusler compounds are used to adjust the degree of spin polarization at the Fermi energy, P, from 60% to 100% and to investigate how they correlate with the damping. It is experimentally demonstrated that the damping decreases when increasing the spin polarization from 1.1 × 10-3 for Co2 MnAl with 63% spin polarization to an ultralow value of 4.6 × 10-4 for the half-metallic ferromagnet Co2 MnSi. This allows the investigation of the relation between these two parameters and the ultrafast demagnetization time characterizing the loss of magnetization occurring after femtosecond laser pulse excitation. The demagnetization time is observed to be inversely proportional to 1 - P and, as a consequence, to the magnetic damping, which can be attributed to the similarity of the spin angular momentum dissipation processes responsible for these two effects. Altogether, the high-quality Heusler compounds allow control over the band structure and therefore the channel for spin angular momentum dissipation.
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Affiliation(s)
- Charles Guillemard
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
- Synchrotron SOLEIL-CNRS, Saint-Aubin, Gif-sur-Yvette, 91192, France
| | - Wei Zhang
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | - Gregory Malinowski
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | - Claudia de Melo
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | - Jon Gorchon
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | | | - Jaafar Ghanbaja
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | - Stéphane Mangin
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
| | - Patrick Le Fèvre
- Synchrotron SOLEIL-CNRS, Saint-Aubin, Gif-sur-Yvette, 91192, France
| | - Francois Bertran
- Synchrotron SOLEIL-CNRS, Saint-Aubin, Gif-sur-Yvette, 91192, France
| | - Stéphane Andrieu
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, 54500, France
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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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5
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Chen Z, Wang LW. Role of initial magnetic disorder: A time-dependent ab initio study of ultrafast demagnetization mechanisms. SCIENCE ADVANCES 2019; 5:eaau8000. [PMID: 31259238 PMCID: PMC6598756 DOI: 10.1126/sciadv.aau8000] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 05/22/2019] [Indexed: 05/23/2023]
Abstract
Despite more than 20 years of development, the underlying physics of the laser-induced demagnetization process is still debated. We present a fast, real-time time-dependent density functional theory (rt-TDDFT) algorithm together with the phenomenological atomic Landau-Lifshitz-Gilbert model to investigate this problem. Our Hamiltonian considers noncollinear magnetic moment, spin-orbit coupling (SOC), electron-electron, electron-phonon, and electron-light interactions. The algorithm for time evolution achieves hundreds of times of speedup enabling calculation of large systems. Our simulations yield a demagnetization rate similar to experiments. We found that (i) the angular momentum flow from light to the system is not essential and the spin Zeeman effect is negligible. (ii) The phonon can play a role but is not essential. (iii) The initial spin disorder and the self-consistent update of the electron-electron interaction play dominant roles and enhance the demagnetization to the experimentally observed rate. The spin disorder connects the electronic structure theory with the phenomenological three-temperature model.
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Liu B, Niu W, Chen Y, Ruan X, Tang Z, Wang X, Liu W, He L, Li Y, Wu J, Tang S, Du J, Zhang R, Xu Y. Ultrafast Orbital-Oriented Control of Magnetization in Half-Metallic La 0.7 Sr 0.3 MnO 3 Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1806443. [PMID: 30663164 DOI: 10.1002/adma.201806443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/15/2018] [Indexed: 06/09/2023]
Abstract
Manipulating spins by ultrafast pulse laser provides a new avenue to switch the magnetization for spintronic applications. While the spin-orbit coupling is known to play a pivotal role in the ultrafast laser-induced demagnetization, the effect of the anisotropic spin-orbit coupling on the transient magnetization remains an open issue. This study uncovers the role of anisotropic spin-orbit coupling in the spin dynamics in a half-metallic La0.7 Sr0.3 MnO3 film by ultrafast pump-probe technique. The magnetic order is found to be transiently enhanced or attenuated within the initial sub-picosecond when the probe light is tuned to be s- or p-polarized, respectively. The subsequent slow demagnetization amplitude follows the fourfold symmetry of the d x 2 - y 2 orbitals as a function of the polarization angles of the probe light. A model based on the Elliott-Yafet spin-flip scatterings is proposed to reveal that the transient magnetization enhancement is related to the spin-mixed states arising from the anisotropic spin-orbit coupling. The findings provide new insights into the spin dynamics in magnetic systems with anisotropic spin-orbit coupling as well as perspectives for the ultrafast control of information process in spintronic devices.
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Affiliation(s)
- Bo Liu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Wei Niu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Yongda Chen
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Xuezhong Ruan
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Zhixiong Tang
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Xuefeng Wang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
| | - Liang He
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Yao Li
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Jing Wu
- York-Nanjing Joint Center in Spintronics, Department of Electronic Engineering and Department of Physics, The University of York, York, YO10 5DD, UK
| | - Shaolong Tang
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Jun Du
- Department of Physics, Nanjing University, Nanjing, 210093, P. R. China
| | - Rong Zhang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Yongbing Xu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
- York-Nanjing Joint Center in Spintronics, Department of Electronic Engineering and Department of Physics, The University of York, York, YO10 5DD, UK
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Battiato M, Minár J, Wang W, Ndiaye W, Richter MC, Heckmann O, Mariot JM, Parmigiani F, Hricovini K, Cacho C. Distinctive Picosecond Spin Polarization Dynamics in Bulk Half Metals. PHYSICAL REVIEW LETTERS 2018; 121:077205. [PMID: 30169049 DOI: 10.1103/physrevlett.121.077205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Indexed: 06/08/2023]
Abstract
Femtosecond laser excitations in half-metal (HM) compounds are theoretically predicted to induce an exotic picosecond spin dynamics. In particular, conversely to what is observed in conventional metals and semiconductors, the thermalization process in HMs leads to a long living partially thermalized configuration characterized by three Fermi-Dirac distributions for the minority, majority conduction, and majority valence electrons, respectively. Remarkably, these distributions have the same temperature but different chemical potentials. This unusual thermodynamic state is causing a persistent nonequilibrium spin polarization only well above the Fermi energy. Femtosecond spin dynamics experiments performed on Fe_{3}O_{4} by time- and spin-resolved photoelectron spectroscopy support our model. Furthermore, the spin polarization response proves to be very robust and it can be adopted to selectively test the bulk HM character in a wide range of compounds.
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Affiliation(s)
- M Battiato
- School of Physical and Mathematical Sciences, Physics and Applied Physics, Nanyang Technological University, 21 Nanyang Link, Singapore, Singapore
- Institute of Solid State Physics, Technische Universität Wien, Wiedner Hauptstraße 8, 1040 Vienna, Austria
| | - J Minár
- New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - W Wang
- Department of Physics, Biology and Chemistry, Linköping University, 581 83 Linköping, Sweden
| | - W Ndiaye
- Laboratoire de Physique des Matériaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France
| | - M C Richter
- Laboratoire de Physique des Matériaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France
- DRF, IRAMIS, SPEC-CNRS/UMR 3680, Bâtiment 772, L'Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - O Heckmann
- Laboratoire de Physique des Matériaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France
- DRF, IRAMIS, SPEC-CNRS/UMR 3680, Bâtiment 772, L'Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - J-M Mariot
- Sorbonne Université, CNRS (UMR 7614), Laboratoire de Chimie Physique-Matière et Rayonnement, 4 place Jussieu, 75252 Paris Cedex 05, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - F Parmigiani
- Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, 34127 Trieste, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, 34149 Basovizza, Italy
- International Faculty, Universität zu Köln, 50937 Köln, Germany
| | - K Hricovini
- Laboratoire de Physique des Matériaux et des Surfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise, France
- DRF, IRAMIS, SPEC-CNRS/UMR 3680, Bâtiment 772, L'Orme des Merisiers, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - C Cacho
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
- Central Laser Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
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8
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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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9
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Carva K, Baláž P, Radu I. Laser-Induced Ultrafast Magnetic Phenomena. HANDBOOK OF MAGNETIC MATERIALS 2017. [DOI: 10.1016/bs.hmm.2017.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Ultrafast laser induced local magnetization dynamics in Heusler compounds. Sci Rep 2016; 6:38911. [PMID: 27966585 PMCID: PMC5155284 DOI: 10.1038/srep38911] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 11/30/2022] Open
Abstract
The overarching goal of the field of femtomagnetism is to control, via laser light, the magnetic structure of matter on a femtosecond time scale. The temporal limits to the light-magnetism interaction are governed by the fact that the electron spin interacts indirectly with light, with current studies showing a laser induced global loss in the magnetic moment on a time scale of the order of a few 100 s of femtoseconds. In this work, by means of ab-initio calculations, we show that more complex magnetic materials - we use the example of the Heusler and half-Heusler alloys - allow for purely optical excitations to cause a significant change in the local moments on the order of 5 fs. This, being purely optical in nature, represents the ultimate mechanism for the short time scale manipulation of spins. Furthermore, we demonstrate that qualitative behaviour of this rich magnetic response to laser light can be deduced from the ground-state spectrum, thus providing a route to tailoring the response of some complex magnetic materials, like the Heuslers, to laser light by the well established methods for material design from ground-state calculations.
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11
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Mueller BY, Baral A, Vollmar S, Cinchetti M, Aeschlimann M, Schneider HC, Rethfeld B. Feedback effect during ultrafast demagnetization dynamics in ferromagnets. PHYSICAL REVIEW LETTERS 2013; 111:167204. [PMID: 24182297 DOI: 10.1103/physrevlett.111.167204] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Indexed: 05/23/2023]
Abstract
Motivated by the recent controversy about the importance of spin-flip scattering for ultrafast demagnetization in ferromagnets, we study the spin-dependent electron dynamics based on a dynamical Elliott-Yafet mechanism. The key improvement to earlier approaches is the use of a modified Stoner model with a dynamic exchange splitting between majority and minority bands. In the framework of our microscopic model, we find a novel feedback effect between the time-dependent exchange splitting and the spin-flip scattering. This feedback effect allows us to reproduce important properties of the demagnetization dynamics quantitatively. Our results demonstrate that in general Elliott-Yafet spin-flip scattering needs to be taken into account to obtain a microscopic picture of demagnetization dynamics.
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Affiliation(s)
- B Y Mueller
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663 Kaiserslautern, Germany
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12
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Schellekens AJ, Koopmans B. Comparing ultrafast demagnetization rates between competing models for finite temperature magnetism. PHYSICAL REVIEW LETTERS 2013; 110:217204. [PMID: 23745920 DOI: 10.1103/physrevlett.110.217204] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Indexed: 06/02/2023]
Abstract
We investigate a recent controversy in ultrafast magnetization dynamics by comparing the demagnetization rates from two frequently used but competing descriptions for finite temperature magnetism, namely a rigid band structure Stoner-like approach and a system of localized spins. The calculations on the localized spin system show a demagnetization rate and time comparable to experimentally obtained values, whereas the rigid band approach yields negligible demagnetization, even when the microscopic spin-flip process is assumed to be instantaneous. This shows that rigid band structure calculations will never be in quantitative agreement with experiments, irrespective of the investigated microscopic scattering mechanism.
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Affiliation(s)
- A J Schellekens
- Department of Applied Physics, Center for NanoMaterials (cNM), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
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Turgut E, La-o-Vorakiat C, Shaw JM, Grychtol P, Nembach HT, Rudolf D, Adam R, Aeschlimann M, Schneider CM, Silva TJ, Murnane MM, Kapteyn HC, Mathias S. Controlling the competition between optically induced ultrafast spin-flip scattering and spin transport in magnetic multilayers. PHYSICAL REVIEW LETTERS 2013; 110:197201. [PMID: 23705737 DOI: 10.1103/physrevlett.110.197201] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Indexed: 05/06/2023]
Abstract
The study of ultrafast dynamics in magnetic materials provides rich opportunities for greater fundamental understanding of correlated phenomena in solid-state matter, because many of the basic microscopic mechanisms involved are as-yet unclear and are still being uncovered. Recently, two different possible mechanisms have been proposed to explain ultrafast laser induced magnetization dynamics: spin currents and spin-flip scattering. In this work, we use multilayers of Fe and Ni with different metals and insulators as the spacer material to conclusively show that spin currents can have a significant contribution to optically induced magnetization dynamics, in addition to spin-flip scattering processes. Moreover, we can control the competition between these two processes, and in some cases completely suppress interlayer spin currents as a sample undergoes rapid demagnetization. Finally, by reversing the order of the Fe/Ni layers, we experimentally show that spin currents are directional in our samples, predominantly flowing from the top to the bottom layer.
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Affiliation(s)
- Emrah Turgut
- Department of Physics and JILA, University of Colorado, Boulder and NIST, Colorado 80309, USA
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Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network. Nat Commun 2012; 3:999. [PMID: 22893123 DOI: 10.1038/ncomms2007] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/11/2012] [Indexed: 11/08/2022] Open
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