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Hariki A, Dal Din A, Amin OJ, Yamaguchi T, Badura A, Kriegner D, Edmonds KW, Campion RP, Wadley P, Backes D, Veiga LSI, Dhesi SS, Springholz G, Šmejkal L, Výborný K, Jungwirth T, Kuneš J. X-Ray Magnetic Circular Dichroism in Altermagnetic α-MnTe. Phys Rev Lett 2024; 132:176701. [PMID: 38728732 DOI: 10.1103/physrevlett.132.176701] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 02/01/2024] [Accepted: 03/20/2024] [Indexed: 05/12/2024]
Abstract
Altermagnetism is a recently identified magnetic symmetry class combining characteristics of conventional collinear ferromagnets and antiferromagnets, that were regarded as mutually exclusive, and enabling phenomena and functionalities unparalleled in either of the two traditional elementary magnetic classes. In this work we use symmetry, ab initio theory, and experiments to explore x-ray magnetic circular dichroism (XMCD) in the altermagnetic class. As a representative material for our XMCD study we choose α-MnTe with compensated antiparallel magnetic order in which an anomalous Hall effect has been already demonstrated. We predict and experimentally confirm a characteristic XMCD line shape for compensated moments lying in a plane perpendicular to the light propagation vector. Our results highlight the distinct phenomenology in altermagnets of this time-reversal symmetry breaking response, and its potential utility for element-specific spectroscopy and microscopy.
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Affiliation(s)
- A Hariki
- Department of Physics and Electronics, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - A Dal Din
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - O J Amin
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - T Yamaguchi
- Department of Physics and Electronics, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - A Badura
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - D Backes
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - L S I Veiga
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - S S Dhesi
- Diamond Light Source, Chilton OX11 0DE, United Kingdom
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria
| | - L Šmejkal
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
- Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany
| | - K Výborný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - T Jungwirth
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Praha 6 Czech Republic
| | - J Kuneš
- Institute for Solid State Physics, TU Wien, 1040 Vienna, Austria
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czechia
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Poole SF, Amin OJ, Solomon A, Barton LX, Campion RP, Edmonds KW, Wadley P. Thermally stable Peltier controlled vacuum chamber for electrical transport measurements. Rev Sci Instrum 2024; 95:035108. [PMID: 38446000 DOI: 10.1063/5.0186155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 02/13/2024] [Indexed: 03/07/2024]
Abstract
The design, manufacture, and characterization of an inexpensive, temperature-controlled vacuum chamber with millikelvin stability for electrical transport measurements at and near room temperature is reported. A commercially available Peltier device and a high-precision temperature controller are used to actively heat and cool the sample space. The system was designed to minimize thermal fluctuations in spintronic and semiconductor transport measurements, but the general principle is relevant to a wide range of electrical measurement applications. The main issues overcome are the mounting of a sample with a path of high thermal conductivity through to the Peltier device and the heat sinking of the said Peltier device inside a vacuum. A copper slug is used as the mount for a sample, and a large copper block is used as a thermal feedthrough before a passive heat sink is used to cool this block. The Peltier device provides 20 W of heating and cooling power, achieving a maximum range of 30 K below and 40 K above the ambient temperature. The temperature stability is within 5 mK at all set points with an even better performance above the ambient temperature. A vacuum pressure of 10-8 hPa is achievable. As a demonstration, we present experimental results from current-induced electrical switching of a CuMnAs thin film. Transport measurements with and without the Peltier control emphasize the importance of a constant temperature in these applications. The thermal lag between the sample space measurement and the sample itself is observed through magnetoresistance values measured during a temperature sweep.
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Affiliation(s)
- S F Poole
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - O J Amin
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - A Solomon
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - L X Barton
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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3
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Krempaský J, Šmejkal L, D'Souza SW, Hajlaoui M, Springholz G, Uhlířová K, Alarab F, Constantinou PC, Strocov V, Usanov D, Pudelko WR, González-Hernández R, Birk Hellenes A, Jansa Z, Reichlová H, Šobáň Z, Gonzalez Betancourt RD, Wadley P, Sinova J, Kriegner D, Minár J, Dil JH, Jungwirth T. Altermagnetic lifting of Kramers spin degeneracy. Nature 2024; 626:517-522. [PMID: 38356066 PMCID: PMC10866710 DOI: 10.1038/s41586-023-06907-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/28/2023] [Indexed: 02/16/2024]
Abstract
Lifted Kramers spin degeneracy (LKSD) has been among the central topics of condensed-matter physics since the dawn of the band theory of solids1,2. It underpins established practical applications as well as current frontier research, ranging from magnetic-memory technology3-7 to topological quantum matter8-14. Traditionally, LKSD has been considered to originate from two possible internal symmetry-breaking mechanisms. The first refers to time-reversal symmetry breaking by magnetization of ferromagnets and tends to be strong because of the non-relativistic exchange origin15. The second applies to crystals with broken inversion symmetry and tends to be comparatively weaker, as it originates from the relativistic spin-orbit coupling (SOC)16-19. A recent theory work based on spin-symmetry classification has identified an unconventional magnetic phase, dubbed altermagnetic20,21, that allows for LKSD without net magnetization and inversion-symmetry breaking. Here we provide the confirmation using photoemission spectroscopy and ab initio calculations. We identify two distinct unconventional mechanisms of LKSD generated by the altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization20-23. Our observation of the altermagnetic LKSD can have broad consequences in magnetism. It motivates exploration and exploitation of the unconventional nature of this magnetic phase in an extended family of materials, ranging from insulators and semiconductors to metals and superconductors20,21, that have been either identified recently or perceived for many decades as conventional antiferromagnets21,24,25.
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Affiliation(s)
- J Krempaský
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland.
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - S W D'Souza
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic
| | - M Hajlaoui
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University of Linz, Linz, Austria
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University of Linz, Linz, Austria
| | - K Uhlířová
- Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - F Alarab
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - P C Constantinou
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - V Strocov
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - D Usanov
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
| | - W R Pudelko
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
- Physik-Institut, Universität Zürich, Zürich, Switzerland
| | - R González-Hernández
- Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Barranquilla, Colombia
| | - A Birk Hellenes
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Z Jansa
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic
| | - H Reichlová
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Z Šobáň
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | | | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - J Minár
- New Technologies Research Center, University of West Bohemia, Plzeň, Czech Republic.
| | - J H Dil
- Photon Science Division, Paul Scherrer Institut, Villigen, Switzerland
- Institut de Physique, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - T Jungwirth
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
- School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom.
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Amin OJ, Poole SF, Reimers S, Barton LX, Dal Din A, Maccherozzi F, Dhesi SS, Novák V, Krizek F, Chauhan JS, Campion RP, Rushforth AW, Jungwirth T, Tretiakov OA, Edmonds KW, Wadley P. Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature. Nat Nanotechnol 2023; 18:849-853. [PMID: 37157021 PMCID: PMC10427425 DOI: 10.1038/s41565-023-01386-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 03/24/2023] [Indexed: 05/10/2023]
Abstract
Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls in the magnetic order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these textures that have high potential for terahertz dynamics, deflection-free motion and improved size scaling due to the absence of stray field. Here we show that topological spin textures, merons and antimerons, can be generated at room temperature and reversibly moved using electrical pulses in thin-film CuMnAs, a semimetallic antiferromagnet that is a testbed system for spintronic applications. The merons and antimerons are localized on 180° domain walls, and move in the direction of the current pulses. The electrical generation and manipulation of antiferromagnetic merons is a crucial step towards realizing the full potential of antiferromagnetic thin films as active components in high-density, high-speed magnetic memory devices.
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Affiliation(s)
- O J Amin
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK.
| | - S F Poole
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - S Reimers
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Diamond Light Source, Chilton, UK
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, Germany
| | - L X Barton
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - A Dal Din
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | | | | | - V Novák
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - F Krizek
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - J S Chauhan
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - A W Rushforth
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - T Jungwirth
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - O A Tretiakov
- School of Physics, The University of New South Wales, Sydney, New South Wales, Australia
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham, UK
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5
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Godinho J, Reichlová H, Kriegner D, Novák V, Olejník K, Kašpar Z, Šobáň Z, Wadley P, Campion RP, Otxoa RM, Roy PE, Železný J, Jungwirth T, Wunderlich J. Electrically induced and detected Néel vector reversal in a collinear antiferromagnet. Nat Commun 2018; 9:4686. [PMID: 30409971 PMCID: PMC6224378 DOI: 10.1038/s41467-018-07092-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/10/2018] [Indexed: 11/09/2022] Open
Abstract
Antiferromagnets are enriching spintronics research by many favorable properties that include insensitivity to magnetic fields, neuromorphic memory characteristics, and ultra-fast spin dynamics. Designing memory devices with electrical writing and reading is one of the central topics of antiferromagnetic spintronics. So far, such a combined functionality has been demonstrated via 90° reorientations of the Néel vector generated by the current-induced spin orbit torque and sensed by the linear-response anisotropic magnetoresistance. Here we show that in the same antiferromagnetic CuMnAs films as used in these earlier experiments we can also control 180° Néel vector reversals by switching the polarity of the writing current. Moreover, the two stable states with opposite Néel vector orientations in this collinear antiferromagnet can be electrically distinguished by measuring a second-order magnetoresistance effect. We discuss the general magnetic point group symmetries allowing for this electrical readout effect and its specific microscopic origin in CuMnAs.
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Affiliation(s)
- J Godinho
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic. .,Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 12116, Prague 2, Czech Republic.
| | - H Reichlová
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062, Dresden, Germany
| | - D Kriegner
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - V Novák
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - K Olejník
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - Z Kašpar
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - Z Šobáň
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - P Wadley
- School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - R M Otxoa
- Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.,Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia-San Sebastian, 20018, Spain
| | - P E Roy
- Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - J Železný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic
| | - T Jungwirth
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic.,School of Physics and Astronomy, University Of Nottingham, NG7 2RD, Nottingham, United Kingdom
| | - J Wunderlich
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 160 00, Prague 6, Czech Republic. .,Hitachi Cambridge Laboratory, Hitachi Europe LTD, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.
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6
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Wadley P, Edmonds KW, Shahedkhah MR, Campion RP, Gallagher BL, Železný J, Kuneš J, Novák V, Jungwirth T, Saidl V, Němec P, Maccherozzi F, Dhesi SS. Control of antiferromagnetic spin axis orientation in bilayer Fe/CuMnAs films. Sci Rep 2017; 7:11147. [PMID: 28894219 PMCID: PMC5593844 DOI: 10.1038/s41598-017-11653-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 08/25/2017] [Indexed: 11/22/2022] Open
Abstract
Using x-ray magnetic circular and linear dichroism techniques, we demonstrate a collinear exchange coupling between an epitaxial antiferromagnet, tetragonal CuMnAs, and an Fe surface layer. A small uncompensated Mn magnetic moment is observed which is antiparallel to the Fe magnetization. The staggered magnetization of the 5 nm thick CuMnAs layer is rotatable under small magnetic fields, due to the interlayer exchange coupling. This allows us to obtain the x-ray magnetic linear dichroism spectra for different crystalline orientations of CuMnAs in the (001) plane. This is a key parameter for enabling the understanding of domain structures in CuMnAs imaged using x-ray magnetic linear dichroism microscopy techniques.
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Affiliation(s)
- P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - M R Shahedkhah
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - B L Gallagher
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - J Železný
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00, Praha 6, Czech Republic.,Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - J Kuneš
- Institute of Physics, Czech Academy of Sciences, Na Slovance 1999/2, 182 21, Praha 8, Czech Republic.,Institute of Solid State Physics, TU Wien, Wiedner Hauptstr. 8, 1040, Wien, Austria
| | - V Novák
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00, Praha 6, Czech Republic
| | - T Jungwirth
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.,Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00, Praha 6, Czech Republic
| | - V Saidl
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00, Praha 6, Czech Republic.,Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic
| | - P Němec
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic
| | - F Maccherozzi
- Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE, United Kingdom
| | - S S Dhesi
- Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE, United Kingdom
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7
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Grzybowski MJ, Wadley P, Edmonds KW, Beardsley R, Hills V, Campion RP, Gallagher BL, Chauhan JS, Novak V, Jungwirth T, Maccherozzi F, Dhesi SS. Imaging Current-Induced Switching of Antiferromagnetic Domains in CuMnAs. Phys Rev Lett 2017; 118:057701. [PMID: 28211721 DOI: 10.1103/physrevlett.118.057701] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Indexed: 05/22/2023]
Abstract
The magnetic order in antiferromagnetic materials is hard to control with external magnetic fields. Using x-ray magnetic linear dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the antiferromagnetic domain structure in microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between the average domain orientation and the anisotropy of the electrical resistance is demonstrated, with both showing reproducible switching in response to orthogonally applied current pulses. However, the behavior is inhomogeneous at the submicron level, highlighting the complex nature of the switching process in multidomain antiferromagnetic films.
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Affiliation(s)
- M J Grzybowski
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - R Beardsley
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - V Hills
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - B L Gallagher
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - J S Chauhan
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - V Novak
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 00 Praha 6, Czech Republic
| | - T Jungwirth
- School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 00 Praha 6, Czech Republic
| | - F Maccherozzi
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - S S Dhesi
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
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8
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9
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Jungwirth T, Marti X, Wadley P, Wunderlich J. Antiferromagnetic spintronics. Nat Nanotechnol 2016; 11:231-41. [PMID: 26936817 DOI: 10.1038/nnano.2016.18] [Citation(s) in RCA: 432] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/25/2016] [Indexed: 05/22/2023]
Abstract
Antiferromagnetic materials are internally magnetic, but the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets externally invisible. This implies that information stored in antiferromagnetic moments would be invisible to common magnetic probes, insensitive to disturbing magnetic fields, and the antiferromagnetic element would not magnetically affect its neighbours, regardless of how densely the elements are arranged in the device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. Among the outstanding questions is how to manipulate and detect the magnetic state of an antiferromagnet efficiently. In this Review we focus on recent works that have addressed this question. The field of antiferromagnetic spintronics can also be viewed from the general perspectives of spin transport, magnetic textures and dynamics, and materials research. We briefly mention this broader context, together with an outlook of future research and applications of antiferromagnetic spintronics.
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Affiliation(s)
- T Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - X Marti
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - J Wunderlich
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
- Hitachi Cambridge Laboratory, Cambridge CB3 0HE, UK
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10
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Wadley P, Howells B, Železný J, Andrews C, Hills V, Campion RP, Novák V, Olejník K, Maccherozzi F, Dhesi SS, Martin SY, Wagner T, Wunderlich J, Freimuth F, Mokrousov Y, Kuneš J, Chauhan JS, Grzybowski MJ, Rushforth AW, Edmonds KW, Gallagher BL, Jungwirth T. Electrical switching of an antiferromagnet. Science 2016; 351:587-90. [PMID: 26841431 DOI: 10.1126/science.aab1031] [Citation(s) in RCA: 297] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 01/04/2016] [Indexed: 11/02/2022]
Abstract
Antiferromagnets are hard to control by external magnetic fields because of the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization. However, relativistic quantum mechanics allows for generating current-induced internal fields whose sign alternates with the periodicity of the antiferromagnetic lattice. Using these fields, which couple strongly to the antiferromagnetic order, we demonstrate room-temperature electrical switching between stable configurations in antiferromagnetic CuMnAs thin-film devices by applied current with magnitudes of order 10(6) ampere per square centimeter. Electrical writing is combined in our solid-state memory with electrical readout and the stored magnetic state is insensitive to and produces no external magnetic field perturbations, which illustrates the unique merits of antiferromagnets for spintronics.
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Affiliation(s)
- P Wadley
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
| | - B Howells
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - J Železný
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic. Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - C Andrews
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - V Hills
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - R P Campion
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - V Novák
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - K Olejník
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - F Maccherozzi
- Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE, UK
| | - S S Dhesi
- Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE, UK
| | - S Y Martin
- Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - T Wagner
- Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK. Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0HE, UK
| | - J Wunderlich
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic. Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - F Freimuth
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - Y Mokrousov
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - J Kuneš
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - J S Chauhan
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - M J Grzybowski
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK. Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02-668 Warsaw, Poland
| | - A W Rushforth
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - B L Gallagher
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - T Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
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11
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Wadley P, Hills V, Shahedkhah MR, Edmonds KW, Campion RP, Novák V, Ouladdiaf B, Khalyavin D, Langridge S, Saidl V, Nemec P, Rushforth AW, Gallagher BL, Dhesi SS, Maccherozzi F, Železný J, Jungwirth T. Antiferromagnetic structure in tetragonal CuMnAs thin films. Sci Rep 2015; 5:17079. [PMID: 26602978 PMCID: PMC4658521 DOI: 10.1038/srep17079] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 10/26/2015] [Indexed: 12/03/2022] Open
Abstract
Tetragonal CuMnAs is an antiferromagnetic material with favourable properties for applications in spintronics. Using a combination of neutron diffraction and x-ray magnetic linear dichroism, we determine the spin axis and magnetic structure in tetragonal CuMnAs, and reveal the presence of an interfacial uniaxial magnetic anisotropy. From the temperature-dependence of the neutron diffraction intensities, the Néel temperature is shown to be (480 ± 5) K. Ab initio calculations indicate a weak anisotropy in the (ab) plane for bulk crystals, with a large anisotropy energy barrier between in-plane and perpendicular-to-plane directions.
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Affiliation(s)
- P. Wadley
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - V. Hills
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - M. R. Shahedkhah
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - K. W. Edmonds
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - R. P. Campion
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - V. Novák
- Institute of Physics ASCR, v. v. i., Cukrovarnicka 10, 16253 Prague 6, Czech Republic
| | - B. Ouladdiaf
- Institut Laue-Langevin, 6 Rue Jules Horowitz, 38042 Grenoble, France
| | - D. Khalyavin
- ISIS, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Science and Technology Facilities Council, Oxon OX11 0QX, United Kingdom
| | - S. Langridge
- ISIS, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Science and Technology Facilities Council, Oxon OX11 0QX, United Kingdom
| | - V. Saidl
- Faculty of Mathematics and Physics, Charles University in Prague, 121 16 Prague, Czech Republic
| | - P. Nemec
- Faculty of Mathematics and Physics, Charles University in Prague, 121 16 Prague, Czech Republic
| | - A. W. Rushforth
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - B. L. Gallagher
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
| | - S. S. Dhesi
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - F. Maccherozzi
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - J. Železný
- Institute of Physics ASCR, v. v. i., Cukrovarnicka 10, 16253 Prague 6, Czech Republic
- Faculty of Mathematics and Physics, Charles University in Prague, 121 16 Prague, Czech Republic
| | - T. Jungwirth
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, United Kingdom
- Institute of Physics ASCR, v. v. i., Cukrovarnicka 10, 16253 Prague 6, Czech Republic
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12
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Marti X, Fina I, Frontera C, Liu J, Wadley P, He Q, Paull RJ, Clarkson JD, Kudrnovský J, Turek I, Kuneš J, Yi D, Chu JH, Nelson CT, You L, Arenholz E, Salahuddin S, Fontcuberta J, Jungwirth T, Ramesh R. Room-temperature antiferromagnetic memory resistor. Nat Mater 2014; 13:367-374. [PMID: 24464243 DOI: 10.1038/nmat3861] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 12/10/2013] [Indexed: 06/03/2023]
Abstract
The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.
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Affiliation(s)
- X Marti
- 1] Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA [2] Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116 Praha 2, Czech Republic [3] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - I Fina
- 1] Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain [2] Max Planck Institute of Microstructure Physics, Weinberg 2, Halle D-06120, Germany
| | - C Frontera
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain
| | - Jian Liu
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - P Wadley
- 1] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic [2] School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - Q He
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R J Paull
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA
| | - J D Clarkson
- Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA
| | - J Kudrnovský
- Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - I Turek
- 1] Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 12116 Praha 2, Czech Republic [2] Institute of Physics of Materials ASCR, v.v.i., Zizkova 22, Brno 616 62, Czech Republic
| | - J Kuneš
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - D Yi
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J-H Chu
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C T Nelson
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - L You
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S Salahuddin
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720, USA
| | - J Fontcuberta
- Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, Bellaterra E-08193, Spain
| | - T Jungwirth
- 1] Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic [2] School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK
| | - R Ramesh
- 1] Department of Materials Science and Engineering and Department of Physics, University of California, Berkeley, California 94720, USA [2] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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13
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Wadley P, Crespi A, Gázquez J, Roldán M, García P, Novak V, Campion R, Jungwirth T, Rinaldi C, Martí X, Holy V, Frontera C, Rius J. Obtaining the structure factors for an epitaxial film using Cu X-ray radiation. J Appl Crystallogr 2013. [DOI: 10.1107/s002188981302414x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Determining atomic positions in thin films by X-ray diffraction is, at present, a task reserved for synchrotron facilities. Here an experimental method is presented which enables the determination of the structure factor amplitudes of thin films using laboratory-based equipment (Cu Kα radiation). This method was tested using an epitaxial 130 nm film of CuMnAs grown on top of a GaAs substrate, which unlike the orthorhombic bulk phase forms a crystal structure with tetragonal symmetry. From the set of structure factor moduli obtained by applying this method, the solution and refinement of the crystal structure of the film has been possible. The results are supported by consistent high-resolution scanning transmission electron microscopy and stoichiometry analyses.
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14
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Butkovičová D, Marti X, Saidl V, Schmoranzerová-Rozkotová E, Wadley P, Holý V, Nĕmec P. Critical role of the sample preparation in experiments using piezoelectric actuators inducing uniaxial or biaxial strains. Rev Sci Instrum 2013; 84:103902. [PMID: 24182124 DOI: 10.1063/1.4823520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report on a systematic study of the stress transferred from an electromechanical piezo-stack into GaAs wafers under a wide variety of experimental conditions. We show that the strains in the semiconductor lattice, which were monitored in situ by means of X-ray diffraction, are strongly dependent on both the wafer thickness and on the selection of the glue which is used to bond the wafer to the piezoelectric actuator. We have identified an optimal set of parameters that reproducibly transfers the largest distortions at room temperature. We have studied strains produced not only by the frequently used uniaxial piezostressors but also by the biaxial ones which replicate the routinely performed experiments using substrate-induced strains but with the advantage of a continuously tunable lattice distortion. The time evolution of the strain response and the sample tilting and/or bending are also analyzed and discussed.
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Affiliation(s)
- D Butkovičová
- Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
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