1
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Makiuchi T, Hioki T, Shimizu H, Hoshi K, Elyasi M, Yamamoto K, Yokoi N, Serga AA, Hillebrands B, Bauer GEW, Saitoh E. Persistent magnetic coherence in magnets. Nat Mater 2024; 23:627-632. [PMID: 38321239 DOI: 10.1038/s41563-024-01798-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 01/05/2024] [Indexed: 02/08/2024]
Abstract
When excited, the magnetization in a magnet precesses around the field in an anticlockwise manner on a timescale governed by viscous magnetization damping, after which any information carried by the initial actuation seems to be lost. This damping appears to be a fundamental bottleneck for the use of magnets in information processing. However, here we demonstrate the recall of the magnetization-precession phase after times that exceed the damping timescale by two orders of magnitude using dedicated two-colour microwave pump-probe experiments for a Y3Fe5O12 microstructured film. Time-resolved magnetization state tomography confirms the persistent magnetic coherence by revealing a double-exponential decay of magnetization correlation. We attribute persistent magnetic coherence to a feedback effect, that is, coherent coupling of the uniform precession with long-lived excitations at the minima of the spin-wave dispersion relation. Our finding liberates magnetic systems from the strong damping in nanostructures that has limited their use in coherent information storage and processing.
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Affiliation(s)
- T Makiuchi
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- Quantum-Phase Electronics Center, University of Tokyo, Tokyo, Japan
| | - T Hioki
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - H Shimizu
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
| | - K Hoshi
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, University of Tokyo, Tokyo, Japan
| | - M Elyasi
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - K Yamamoto
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Japan
| | - N Yokoi
- Department of Applied Physics, University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, University of Tokyo, Tokyo, Japan
| | - A A Serga
- Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | - B Hillebrands
- Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | - G E W Bauer
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Kavli Institute for Theoretical Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - E Saitoh
- Department of Applied Physics, University of Tokyo, Tokyo, Japan.
- Quantum-Phase Electronics Center, University of Tokyo, Tokyo, Japan.
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Institute for AI and Beyond, University of Tokyo, Tokyo, Japan.
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Japan.
- RIKEN Center for Emergent Matter Science, Wako, Japan.
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2
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Rongione E, Gueckstock O, Mattern M, Gomonay O, Meer H, Schmitt C, Ramos R, Kikkawa T, Mičica M, Saitoh E, Sinova J, Jaffrès H, Mangeney J, Goennenwein STB, Geprägs S, Kampfrath T, Kläui M, Bargheer M, Seifert TS, Dhillon S, Lebrun R. Emission of coherent THz magnons in an antiferromagnetic insulator triggered by ultrafast spin-phonon interactions. Nat Commun 2023; 14:1818. [PMID: 37002246 PMCID: PMC10066367 DOI: 10.1038/s41467-023-37509-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Antiferromagnetic materials have been proposed as new types of narrowband THz spintronic devices owing to their ultrafast spin dynamics. Manipulating coherently their spin dynamics, however, remains a key challenge that is envisioned to be accomplished by spin-orbit torques or direct optical excitations. Here, we demonstrate the combined generation of broadband THz (incoherent) magnons and narrowband (coherent) magnons at 1 THz in low damping thin films of NiO/Pt. We evidence, experimentally and through modeling, two excitation processes of spin dynamics in NiO: an off-resonant instantaneous optical spin torque in (111) oriented films and a strain-wave-induced THz torque induced by ultrafast Pt excitation in (001) oriented films. Both phenomena lead to the emission of a THz signal through the inverse spin Hall effect in the adjacent heavy metal layer. We unravel the characteristic timescales of the two excitation processes found to be < 50 fs and > 300 fs, respectively, and thus open new routes towards the development of fast opto-spintronic devices based on antiferromagnetic materials.
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Affiliation(s)
- E Rongione
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - O Gueckstock
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany
| | - M Mattern
- Institut für Physik und Astronomie, Universität Potsdam, D-14476, Potsdam, Germany
| | - O Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - H Meer
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - C Schmitt
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - R Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, J-980-8577, Japan
- Centro Singular de Investigación en Química Bilóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - T Kikkawa
- Department of Applied Physics, The University of Tokyo, Tokyo, J-113-8656, Japan
| | - M Mičica
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - E Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, J-980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, J-113-8656, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, J-113-8656, Japan
| | - J Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - H Jaffrès
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France
| | - J Mangeney
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - S T B Goennenwein
- Department of Physics, University of Konstanz, D-78457, Konstanz, Germany
| | - S Geprägs
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748, Garching, Germany
| | - T Kampfrath
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany
| | - M Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz (MAINZ), Staudingerweg 9, D-55128, Mainz, Germany
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, N-7034, Trondheim, Norway
| | - M Bargheer
- Institut für Physik und Astronomie, Universität Potsdam, D-14476, Potsdam, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Strasse 15, D-12489, Berlin, Germany
| | - T S Seifert
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany.
| | - S Dhillon
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - R Lebrun
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France.
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3
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Jiang N, Nii Y, Arisawa H, Saitoh E, Ohe J, Onose Y. Chirality Memory Stored in Magnetic Domain Walls in the Ferromagnetic State of MnP. Phys Rev Lett 2021; 126:177205. [PMID: 33988392 DOI: 10.1103/physrevlett.126.177205] [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: 10/02/2020] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Chirality in a helimagnetic structure is determined by the sense of magnetic moment rotation. We found that the chiral information did not disappear even after the phase transition to the high-temperature ferromagnetic phase in a helimagnet MnP. The 2nd harmonic resistivity ρ^{2f}, which reflects the breaking down of mirror symmetry, was found to be almost unchanged after heating the sample above the ferromagnetic transition temperature and cooling it back to the helimagnetic state. The application of a magnetic field along the easy axis in the ferromagnetic state quenched the chirality-induced ρ^{2f}. This indicates that the chirality memory effect originated from the ferromagnetic domain walls.
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Affiliation(s)
- N Jiang
- Department of Basic Science, The University of Tokyo, Tokyo 153-8902, Japan
| | - Y Nii
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - H Arisawa
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - J Ohe
- Department of Physics, Toho University, 2-2-1 Miyama, Funabashi 274-8510, Japan
| | - Y Onose
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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4
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Baldrati L, Schmitt C, Gomonay O, Lebrun R, Ramos R, Saitoh E, Sinova J, Kläui M. Efficient Spin Torques in Antiferromagnetic CoO/Pt Quantified by Comparing Field- and Current-Induced Switching. Phys Rev Lett 2020; 125:077201. [PMID: 32857543 DOI: 10.1103/physrevlett.125.077201] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/02/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
We achieve current-induced switching in collinear insulating antiferromagnetic CoO/Pt, with fourfold in-plane magnetic anisotropy. This is measured electrically by spin Hall magnetoresistance and confirmed by the magnetic field-induced spin-flop transition of the CoO layer. By applying current pulses and magnetic fields, we quantify the efficiency of the acting current-induced torques and estimate a current-field equivalence ratio of 4×10^{-11} T A^{-1} m^{2}. The Néel vector final state (n⊥j) is in line with a thermomagnetoelastic switching mechanism for a negative magnetoelastic constant of the CoO.
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Affiliation(s)
- L Baldrati
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - C Schmitt
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - O Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - R Lebrun
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Unité Mixte de Physique CNRS, Thales, Université Paris-Sud, Université Paris-Saclay, Palaiseau 91767, France
| | - R Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - E Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - J Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Praha 11720, Czech Republic
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
| | - M Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
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5
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Nambu Y, Barker J, Okino Y, Kikkawa T, Shiomi Y, Enderle M, Weber T, Winn B, Graves-Brook M, Tranquada JM, Ziman T, Fujita M, Bauer GEW, Saitoh E, Kakurai K. Observation of Magnon Polarization. Phys Rev Lett 2020; 125:027201. [PMID: 32701305 DOI: 10.1103/physrevlett.125.027201] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
We measure the mode-resolved direction of the precessional motion of the magnetic order, i.e., magnon polarization, via the chiral term of inelastic polarized neutron scattering spectra. The magnon polarization is a unique and unambiguous signature of magnets and is important in spintronics, affecting thermodynamic properties such as the magnitude and sign of the spin Seebeck effect. However, it has never been directly measured in any material until this work. The observation of both signs of magnon polarization in Y_{3}Fe_{5}O_{12} also gives direct proof of its ferrimagnetic nature. The experiments agree very well with atomistic simulations of the scattering cross section.
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Affiliation(s)
- Y Nambu
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - J Barker
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Y Okino
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Kikkawa
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- WPI-AIMR, Tohoku University, Sendai 980-8577, Japan
| | - Y Shiomi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - M Enderle
- Institut Laue-Langevin (ILL), 38042 Grenoble, France
| | - T Weber
- Institut Laue-Langevin (ILL), 38042 Grenoble, France
| | - B Winn
- Oak Ridge National Lab (ORNL), Oak Ridge, Tennessee 37831, USA
| | - M Graves-Brook
- Oak Ridge National Lab (ORNL), Oak Ridge, Tennessee 37831, USA
| | - J M Tranquada
- Brookhaven National Lab (BNL), Upton, New York 11973-5000, USA
| | - T Ziman
- Institut Laue-Langevin (ILL), 38042 Grenoble, France
- Université Grenoble Alpes, CNRS, LPMMC, 38000 Grenoble, France
| | - M Fujita
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - G E W Bauer
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- WPI-AIMR, Tohoku University, Sendai 980-8577, Japan
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, Netherlands
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- WPI-AIMR, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
| | - K Kakurai
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Saitama 351-0198, Japan
- Materials Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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6
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Takahashi R, Chudo H, Matsuo M, Harii K, Ohnuma Y, Maekawa S, Saitoh E. Giant spin hydrodynamic generation in laminar flow. Nat Commun 2020; 11:3009. [PMID: 32541678 PMCID: PMC7295809 DOI: 10.1038/s41467-020-16753-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 08/15/2018] [Accepted: 05/20/2020] [Indexed: 11/18/2022] Open
Abstract
Hydrodynamic motion can generate a flux of electron-spin’s angular momentum via the coupling between fluid rotation and electron spins. Such hydrodynamic generation, called spin hydrodynamic generation (SHDG), has recently attracted attention in a wide range of fields, especially in spintronics. Spintronics deals with spin-mediated interconversion taking place on a micro or nano scale because of the spin-diffusion length scale. To be fully incorporated into the interconversion, SHDG physics should also be established in such a minute scale, where most fluids exhibit a laminar flow. Here, we report electric voltage generation due to the SHDG in a laminar flow of a liquid-metal mercury. The experimental results show a scaling rule unique to the laminar-flow SHDG. Furthermore, its energy conversion efficiency turns out to be about 105 greater than of the turbulent one. Our findings reveal that the laminar-flow SHDG is suitable to downsizing and to extend the coverage of fluid spintronics. In spin hydrodynamic generation originating from the coupling of mechanical rotation in a fluid and electron spin, fluid vorticity can be converted into an electric voltage via a spin current. Here, the authors demonstrate experimentally that the energy conversion in a laminar flow regime is strongly enhanced over the turbulent regime.
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Affiliation(s)
- R Takahashi
- Natural Science Division, Faculty of Core Research, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan. .,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan. .,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.
| | - H Chudo
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan
| | - M Matsuo
- Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.,Advanced Institute for Material Research, Tohoku University, Sendai, 980-8577, Japan.,Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.,CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, China.,Riken Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - K Harii
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.,Department of Advanced Functional Materials Research, National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma, 370-1292, Japan
| | - Y Ohnuma
- Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.,Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - S Maekawa
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.,Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.,Riken Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - E Saitoh
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai, 980-8577, Japan.,Advanced Institute for Material Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Department of Applied Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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7
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Ramos R, Hioki T, Hashimoto Y, Kikkawa T, Frey P, Kreil AJE, Vasyuchka VI, Serga AA, Hillebrands B, Saitoh E. Room temperature and low-field resonant enhancement of spin Seebeck effect in partially compensated magnets. Nat Commun 2019; 10:5162. [PMID: 31727884 PMCID: PMC6856150 DOI: 10.1038/s41467-019-13121-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [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: 03/21/2019] [Accepted: 10/08/2019] [Indexed: 11/09/2022] Open
Abstract
Resonant enhancement of spin Seebeck effect (SSE) due to phonons was recently discovered in Y[Formula: see text]Fe[Formula: see text]O[Formula: see text] (YIG). This effect is explained by hybridization between the magnon and phonon dispersions. However, this effect was observed at low temperatures and high magnetic fields, limiting the scope for applications. Here we report observation of phonon-resonant enhancement of SSE at room temperature and low magnetic field. We observe in Lu[Formula: see text]BiFe[Formula: see text]GaO[Formula: see text] an enhancement 700% greater than that in a YIG film and at very low magnetic fields around 10[Formula: see text] T, almost one order of magnitude lower than that of YIG. The result can be explained by the change in the magnon dispersion induced by magnetic compensation due to the presence of non-magnetic ion substitutions. Our study provides a way to tune the magnon response in a crystal by chemical doping, with potential applications for spintronic devices.
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Affiliation(s)
- R Ramos
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
| | - T Hioki
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Y Hashimoto
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - T Kikkawa
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - P Frey
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - A J E Kreil
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - V I Vasyuchka
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - A A Serga
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - B Hillebrands
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663, Kaiserslautern, Germany
| | - E Saitoh
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656, Japan.,Center for Spintronics Research Network, Tohoku University, Sendai, 980-8577, Japan.,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan
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8
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Baldrati L, Gomonay O, Ross A, Filianina M, Lebrun R, Ramos R, Leveille C, Fuhrmann F, Forrest TR, Maccherozzi F, Valencia S, Kronast F, Saitoh E, Sinova J, Kläui M. Mechanism of Néel Order Switching in Antiferromagnetic Thin Films Revealed by Magnetotransport and Direct Imaging. Phys Rev Lett 2019; 123:177201. [PMID: 31702247 DOI: 10.1103/physrevlett.123.177201] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 08/07/2019] [Indexed: 06/10/2023]
Abstract
We probe the current-induced magnetic switching of insulating antiferromagnet-heavy-metal systems, by electrical spin Hall magnetoresistance measurements and direct imaging, identifying a reversal occurring by domain wall (DW) motion. We observe switching of more than one-third of the antiferromagnetic domains by the application of current pulses. Our data reveal two different magnetic switching mechanisms leading together to an efficient switching, namely, the spin-current induced effective magnetic anisotropy variation and the action of the spin torque on the DWs.
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Affiliation(s)
- L Baldrati
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - O Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - A Ross
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
| | - M Filianina
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
| | - R Lebrun
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - R Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - C Leveille
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - F Fuhrmann
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - T R Forrest
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - F Maccherozzi
- Diamond Light Source, Chilton, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - S Valencia
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - F Kronast
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - E Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
| | - J Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - M Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany
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9
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Ogawa M, Kagaya H, Shibata S, Inamoto Y, Aoyagi Y, Onogi K, Mori S, Akahori R, Saitoh E. Swallowing rounds in patients with dysphagia. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.1056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Kagaya H, Ogawa M, Mori S, Aoyagi Y, Shibata S, Onogi K, Inamoto Y, Mori H, Saitoh E. Development of peripheral magnetic stimulation system to stimulate suprahyoid muscles. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Aoyagi Y, Taniguchi H, Imaeda S, Hirumuta M, Kagaya H, Saitoh E. Elicitation of swallowing reflex by esophageal stimulation in healthy subjects – Evaluation using high resolution manometry. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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12
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Hirano S, Saitoh E, Kagaya H, Sonoda S, Mukaino M, Tsunoda T, Tanabe S, Yamada J, Suzuki A, Konosu H. Welwalk facilitate early improvement in walking independence of stroke patients with hemiplegia. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Mizokoshi E, Kagaya H, Aoyagi Y, Shibata S, Onogi K, Inamoto Y, Pongpipatpaiboon K, Saitoh E. Factors affecting aspiration in chew-swallow and discrete swallow in stroke patients. Ann Phys Rehabil Med 2018. [DOI: 10.1016/j.rehab.2018.05.420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Taniguchi H, Aoyagi Y, Matsuo K, Nakagawa K, Saitoh E. Development of an oesophageal stimulation method to elicit swallowing reflex in humans. J Oral Rehabil 2017; 45:211-215. [PMID: 29247533 DOI: 10.1111/joor.12599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2017] [Indexed: 12/16/2022]
Abstract
Swallowing reflex is known to be evoked by gastroesophageal regurgitation or oesophageal stimulation in animal studies. However, details regarding the stimulating material, bolus size and stimulation area remain unclear for the stimulation-induced type of swallowing reflex in humans. Here, we evaluated the effects of different kinds of stimulation via water and air injection of the oesophagus on the initiation of the swallowing reflex. Nine healthy individuals participated in this study. A fibre-optic endoscope was passed transnasally, and a thin catheter for injection was passed through the other side. The tip of the catheter was placed at the upper, upper middle, lower middle or lower region of the oesophagus, and the rate of injection was controlled at 0.2 mL/s. Swallowing reflex latency was calculated as the time from injection via air or thin/thick fluid until the onset of white-out in endoscopic images. Reflex latency was significantly shorter when injection occurred at the upper region of the oesophagus than at the lower region, for both thin and thick fluids (P < .01). At the upper region of the oesophagus, the latency was significantly shorter after injection of thin fluid than with thick fluid (P < .05). Injection of air did not induce the swallowing reflex at all sites. These findings suggest that while the swallowing reflex is evoked by stimulation via fluid injection of the oesophagus in humans, sensitivity is greatest in the upper region of the oesophagus compared with the lower region and can vary depending on the injecting material.
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Affiliation(s)
- H Taniguchi
- Department of Dentistry, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Y Aoyagi
- Department of Rehabilitation Medicine, School of Medicine, Fujita Health University, Toyoake, Japan
| | - K Matsuo
- Department of Dentistry, School of Medicine, Fujita Health University, Toyoake, Japan
| | - K Nakagawa
- Department of Dentistry, School of Medicine, Fujita Health University, Toyoake, Japan
| | - E Saitoh
- Department of Rehabilitation Medicine, School of Medicine, Fujita Health University, Toyoake, Japan
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15
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Shibata S, Inamoto Y, Saitoh E, Kagaya H, Aoyagi Y, Ota K, Akahori R, Fujii N, Palmer JB, González-Fernández M. The effect of bolus volume on laryngeal closure and UES opening in swallowing: Kinematic analysis using 320-row area detector CT study. J Oral Rehabil 2017; 44:974-981. [PMID: 28891595 DOI: 10.1111/joor.12573] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2017] [Indexed: 01/09/2023]
Abstract
This study investigated the effects of three different volumes of honey-thick liquid on the temporal characteristics of swallowing. Twenty-six healthy subjects (15 males, 11 females) underwent 320-row area detector CT scan while swallowing 3, 10 and 20 mL of honey-thick liquid barium. Three-dimensional images were created at 10 images/s. Kinematic events involving six structures (velopharynx, hyoid bone, epiglottis, laryngeal vestibule (LV), true vocal cords (TVC), upper esophageal sphincter (UES)) and timing of bolus movement were timed using frame by frame analysis. The overall sequence of events did not differ across three volumes; however, increasing bolus volume significantly changed the onset and termination of events. The bolus head reached to pharynx and esophagus earlier and the duration of bolus passing through UES was significantly longer in 10 and 20 mL compared to 3 mL (P < .05). Consequently, the onset of UES opening was significantly earlier with increased volume (P < .05). LV and TVC closure occurred later in 20 mL compared to 3 mL (P < .05). These changes in motion of pharynx and larynx appeared to promote swallow safety by preventing aspiration, suggesting that anatomical structure movements adapt in response to bolus volume. Our findings also suggest that the pharyngeal swallow behaviours may be modified by afferents in the oral cavity. The three-dimensional visualization and quantitative measurements provided by 320-ADCT provide essential benchmarks for understanding swallowing, both normal and abnormal.
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Affiliation(s)
- S Shibata
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Y Inamoto
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan.,Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - E Saitoh
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - H Kagaya
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Y Aoyagi
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - K Ota
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - R Akahori
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - N Fujii
- Department of Radiology, School of Medicine, Fujita Health University, Toyoake, Japan
| | - J B Palmer
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, USA
| | - M González-Fernández
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD, USA
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16
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Kobayashi D, Yoshikawa T, Matsuo M, Iguchi R, Maekawa S, Saitoh E, Nozaki Y. Spin Current Generation Using a Surface Acoustic Wave Generated via Spin-Rotation Coupling. Phys Rev Lett 2017; 119:077202. [PMID: 28949686 DOI: 10.1103/physrevlett.119.077202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate the generation of alternating spin current (SC) via spin-rotation coupling (SRC) using a surface acoustic wave (SAW) in a Cu film. Ferromagnetic resonance caused by injecting SAWs was observed in a Ni-Fe film attached to a Cu film, with the resonance further found to be suppressed through the insertion of a SiO_{2} film into the interface. The intensity of the resonance depended on the angle between the wave vector of the SAW and the magnetization of the Ni-Fe film. This angular dependence is explicable in terms of the presence of spin transfer torque from a SC generated via SRC.
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Affiliation(s)
- D Kobayashi
- Department of Physics, Keio University, Yokohama 223-8522, Japan
| | - T Yoshikawa
- Department of Physics, Keio University, Yokohama 223-8522, Japan
| | - M Matsuo
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - R Iguchi
- National Institute for Materials Science, Tsukuba 305-0047, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Maekawa
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
| | - E Saitoh
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
| | - Y Nozaki
- Department of Physics, Keio University, Yokohama 223-8522, Japan
- Center for Spintronics Research Network, Keio University, Yokohama 223-8522, Japan
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17
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Shiomi Y, Lustikova J, Saitoh E. Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films. Sci Rep 2017; 7:5358. [PMID: 28706217 PMCID: PMC5509755 DOI: 10.1038/s41598-017-05747-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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: 03/07/2017] [Accepted: 04/26/2017] [Indexed: 11/25/2022] Open
Abstract
Although magnetism and superconductivity hardly coexist in a single material, recent advances in nanotechnology and spintronics have brought to light their interplay in magnetotransport in thin-film heterostructures. Here, we found a periodic oscillation of Nernst voltage with respect to magnetic fields in Pt|LiFe5O8 (Pt|LFO) bilayers grown on a cuprate superconductor YBa2Cu3O7−x (YBCO). At high temperatures above the superconducting transition temperature (TC) of YBCO, spin Seebeck voltages originating in Pt|LFO layers are observed. As temperature decreases well below TC, the spin Seebeck voltage is suppressed and unconventional periodic voltage oscillation as a function of magnetic fields appears; such an oscillation emerging along the Hall direction in the superconducting state has not been observed yet. Dynamics of superconducting vortices pinned by surface precipitates seems responsible for the oscillatory Nernst effect.
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Affiliation(s)
- Y Shiomi
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan. .,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Aoba-ku, Sendai, 980-8577, Japan.
| | - J Lustikova
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Aoba-ku, Sendai, 980-8577, Japan.,WPI Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.,Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, 319-1195, Japan
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18
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Tanabe S, Ii T, Koyama S, Saitoh E, Itoh N, Ohtsuka K, Katoh Y, Shimizu A, Tomita Y. Spatiotemporal treadmill gait measurements using a laser range scanner: feasibility study of the healthy young adults. Physiol Meas 2017; 38:N81-N92. [PMID: 28327472 DOI: 10.1088/1361-6579/aa63d1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Spatio-temporal parameters are typically used for gait analysis. Although these parameters are measured by sophisticated systems such as 3D motion capture system or optoelectronic bars, these systems cannot be deployed easily because of their high costs, large space requirements and elaborate set-up. The purpose of this study is to develope a system for measuring spatiotemporal gait parameters using a laser range scanner during treadmill gait. APPROACH To calculate accurate spatiotemporal parameters, the differences between the laser range scanner measured values and the reference values obtained from a 3D motion capture system were investigated in thirty subjects. From measurements in time and position at foot contact/off, adjustments to compensate for the differences in time and position were derived. Then, to determine the validity of the proposed system, values from the proposed system and the reference system were compared in four additional subjects. MAIN RESULTS The results indicate that the data from the laser range scanner demonstrate certain differences in time and position compared with reference values. However, when compensation values were introduced, each spatiotemporal parameter correlated well with the reference values. SIGNIFICANCE This newer system is smaller, is easier to deploy and requires less training than the 3D motion capture system.
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Affiliation(s)
- S Tanabe
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
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19
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Hou D, Qiu Z, Iguchi R, Sato K, Vehstedt EK, Uchida K, Bauer GEW, Saitoh E. Observation of temperature-gradient-induced magnetization. Nat Commun 2016; 7:12265. [PMID: 27457185 PMCID: PMC4963471 DOI: 10.1038/ncomms12265] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [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: 04/12/2016] [Accepted: 06/16/2016] [Indexed: 12/03/2022] Open
Abstract
Applying magnetic fields has been the method of choice to magnetize non-magnetic materials, but they are difficult to focus. The magneto-electric effect and voltage-induced magnetization generate magnetization by applied electric fields, but only in special compounds or heterostructures. Here we demonstrate that a simple metal such as gold can be magnetized by a temperature gradient or magnetic resonance when in contact with a magnetic insulator by observing an anomalous Hall-like effect, which directly proves the breakdown of time-reversal symmetry. Such Hall measurements give experimental access to the spectral spin Hall conductance of the host metal, which is closely related to other spin caloritronics phenomena such as the spin Nernst effect and serves as a reference for theoretical calculation.
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Affiliation(s)
- Dazhi Hou
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan
| | - Zhiyong Qiu
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan
| | - R. Iguchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K. Sato
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - E. K. Vehstedt
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- London Centre for Nanotechnology and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - K. Uchida
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - G. E. W. Bauer
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Kavli Institute of NanoScience, Delft University of Technology, Delft 2628 CJ, The Netherlands
| | - E. Saitoh
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577, Japan
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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20
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Koyama S, Tanabe S, Saitoh E, Hirano S, Shimizu Y, Katoh M, Uno A, Takemitsu T. Characterization of unexpected postural changes during robot-assisted gait training in paraplegic patients. Spinal Cord 2015; 54:120-5. [PMID: 26261073 DOI: 10.1038/sc.2015.138] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 05/03/2015] [Accepted: 06/22/2015] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN This is a retrospective study. OBJECTIVES The objectives of this study were to categorize unexpected postural changes (UPCs) during gait training in paraplegic patients with wearable gait-assist robots, to reveal the incidence of the UPC and its time-dependent changes during initial gait training period and to investigate neurological level-specific differences. SETTING This study was conducted in Fujita Health University, Aichi, Japan. METHODS We investigated five patients (46.2±14.6 years; lesion level: T6:3, T12:2). All patients had previously achieved gait with wearable robot and walker at supervision level. The UPCs were counted for 2 years and classified according to their type. The time-course data were calculated from the incidence of UPCs for 10 days from initial gait training with the walker. The neurological level-specific differences were investigated between T6 and T12 injuries. RESULTS Eighty-five UPCs were observed and classified into three categories: anterior breakdown, posterior breakdown (PBD) and mal-timing. The average rate over the entire period was 0.96±0.62 (incidents/h/subject). PBD, which was defined as hyperflexion of both hip joints, occurred with the highest frequency (0.64±0.64 incidents/h/subject). During initial gait training, there was a gradual decrease in the occurrence of UPC. For neurological level-specific differences, UPCs were observed more frequently in T6 injuries (1.36±0.35 incidents/h/subject) compared with T12 injuries (0.36±0.31 incidents/h/subject). CONCLUSION PBDs might be the result of near collisions between the trunk of the user and the walker, which make it difficult for the users to move their trunk over an anterior stance limb. Training that is focused upon well-timed forward movements of the walker might be required to avoid the occurrence of this common UPC.
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Affiliation(s)
- S Koyama
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan.,Department of Rehabilitation, Kawamura Hospital, Gifu, Japan
| | - S Tanabe
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - E Saitoh
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - S Hirano
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Y Shimizu
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - M Katoh
- Department of Rehabilitation, Fujita Health University Hospital, Toyoake, Japan
| | - A Uno
- Tomei Brace Company, Seto, Japan
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21
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Inamoto Y, Saitoh E, Okada S, Kagaya H, Shibata S, Baba M, Onogi K, Hashimoto S, Katada K, Wattanapan P, Palmer JB. Anatomy of the larynx and pharynx: effects of age, gender and height revealed by multidetector computed tomography. J Oral Rehabil 2015; 42:670-7. [DOI: 10.1111/joor.12298] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Y. Inamoto
- Department of Rehabilitation Medicine; School of Medicine; Fujita Health University; Aichi Japan
- Faculty of Rehabilitation; School of Health Sciences; Fujita Health University; Aichi Japan
| | - E. Saitoh
- Department of Rehabilitation Medicine; School of Medicine; Fujita Health University; Aichi Japan
| | - S. Okada
- Faculty of Rehabilitation; School of Health Sciences; Fujita Health University; Aichi Japan
| | - H. Kagaya
- Department of Rehabilitation Medicine; School of Medicine; Fujita Health University; Aichi Japan
| | - S. Shibata
- Department of Rehabilitation Medicine; School of Medicine; Fujita Health University; Aichi Japan
| | - M. Baba
- Japanese Red Cross Ashikaga Hospital; Tochigi Japan
| | - K. Onogi
- Department of Rehabilitation Medicine; School of Medicine; Fujita Health University; Aichi Japan
| | - S. Hashimoto
- Department of Hygiene; Fujita Health University; Aichi Japan
| | - K. Katada
- Department of Radiology; Fujita Health University; Aichi Japan
| | - P. Wattanapan
- Institute of Medicine; Suranaree University of Technology; Muang Nakornratchasima, Thailand
| | - J. B. Palmer
- Department of Physical Medicine and Rehabilitation; Department of Otolaryngology-Head and Neck Surgery; and Center for Functional Anatomy and Evolution; Johns Hopkins University; Baltimore Maryland USA
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22
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Uchida K, Adachi H, Kikuchi D, Ito S, Qiu Z, Maekawa S, Saitoh E. Generation of spin currents by surface plasmon resonance. Nat Commun 2015; 6:5910. [PMID: 25569821 PMCID: PMC4354158 DOI: 10.1038/ncomms6910] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [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: 06/27/2014] [Accepted: 11/20/2014] [Indexed: 11/17/2022] Open
Abstract
Surface plasmons, free-electron collective oscillations in metallic nanostructures, provide abundant routes to manipulate light–electron interactions that can localize light energy and alter electromagnetic field distributions at subwavelength scales. The research field of plasmonics thus integrates nano-photonics with electronics. In contrast, electronics is also entering a new era of spintronics, where spin currents play a central role in driving devices. However, plasmonics and spin-current physics have so far been developed independently. Here we report the generation of spin currents by surface plasmon resonance. Using Au nanoparticles embedded in Pt/BiY2Fe5O12 bilayer films, we show that, when the Au nanoparticles fulfill the surface-plasmon-resonance conditions, spin currents are generated across the Pt/BiY2Fe5O12 interface. This spin-current generation cannot be explained by conventional heating effects, requiring us to introduce nonequilibrium magnons excited by surface-plasmon-induced evanescent electromagnetic fields in BiY2Fe5O12. This plasmonic spin pumping integrates surface plasmons with spin-current physics, opening the door to plasmonic spintronics. Optical methods allow for the excitation of diverse magnetic phenomena in nanostructured materials. Here, Uchida et al. demonstrate how pure spin current may be generated across a Pt/BiY2Fe5O12 thin film interface by optically exciting surface plasmon resonance in embedded gold nanoparticles.
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Affiliation(s)
- K Uchida
- 1] Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan [2] PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - H Adachi
- 1] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan [2] CREST, Japan Science and Technology Agency, Tokyo 102-0075, Japan
| | - D Kikuchi
- 1] Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan [2] WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Ito
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Z Qiu
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Maekawa
- 1] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan [2] CREST, Japan Science and Technology Agency, Tokyo 102-0075, Japan
| | - E Saitoh
- 1] Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan [2] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan [3] CREST, Japan Science and Technology Agency, Tokyo 102-0075, Japan [4] WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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23
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Abstract
We have demonstrated spin pumping from a paramagnetic state of an insulator La2NiMnO6 into a Pt film. Single-crystalline films of La2NiMnO6 which exhibit a ferromagnetic order at TC≈270 K were grown by pulsed laser deposition. The inverse spin Hall voltage induced by spin-current injection has been observed in the Pt layer not only in the ferromagnetic phase of La2NiMnO6, but also in a wide temperature range above TC. The efficient spin pumping in the paramagnetic phase is ascribable to ferromagnetic correlation, not to ferromagnetic order.
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Affiliation(s)
- Y Shiomi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan and Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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24
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Shiomi Y, Nomura K, Kajiwara Y, Eto K, Novak M, Segawa K, Ando Y, Saitoh E. Spin-electricity conversion induced by spin injection into topological insulators. Phys Rev Lett 2014; 113:196601. [PMID: 25415913 DOI: 10.1103/physrevlett.113.196601] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Indexed: 06/04/2023]
Abstract
We report successful spin injection into the surface states of topological insulators by using a spin pumping technique. By measuring the voltage that shows up across the samples as a result of spin pumping, we demonstrate that a spin-electricity conversion effect takes place in the surface states of bulk-insulating topological insulators Bi(1.5)Sb(0.5)Te(1.7)Se(1.3) and Sn-doped Bi(2)Te(2)Se. In this process, the injected spins are converted into a charge current along the Hall direction due to the spin-momentum locking on the surface state.
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Affiliation(s)
- Y Shiomi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K Nomura
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Y Kajiwara
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - K Eto
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - M Novak
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Kouji Segawa
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Yoichi Ando
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan and Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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25
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Okamoto N, Kurebayashi H, Trypiniotis T, Farrer I, Ritchie DA, Saitoh E, Sinova J, Mašek J, Jungwirth T, Barnes CHW. Electric control of the spin Hall effect by intervalley transitions. Nat Mater 2014; 13:932-937. [PMID: 25108612 DOI: 10.1038/nmat4059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 07/09/2014] [Indexed: 06/03/2023]
Abstract
Controlling spin-related material properties by electronic means is a key step towards future spintronic technologies. The spin Hall effect (SHE) has become increasingly important for generating, detecting and using spin currents, but its strength--quantified in terms of the SHE angle--is ultimately fixed by the magnitude of the spin-orbit coupling (SOC) present for any given material system. However, if the electrons generating the SHE can be controlled by populating different areas (valleys) of the electronic structure with different SOC characteristic the SHE angle can be tuned directly within a single sample. Here we report the manipulation of the SHE in bulk GaAs at room temperature by means of an electrical intervalley transition induced in the conduction band. The spin Hall angle was determined by measuring an electromotive force driven by photoexcited spin-polarized electrons drifting through GaAs Hall bars. By controlling electron populations in different (Γ and L) valleys, we manipulated the angle from 0.0005 to 0.02. This change by a factor of 40 is unprecedented in GaAs and the highest value achieved is comparable to that of the heavy metal Pt.
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Affiliation(s)
- N Okamoto
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - H Kurebayashi
- 1] Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK [2] London Centre for Nanotechnology, UCL, 17-19 Gordon Street, WC1H 0AH, UK [3] PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - T Trypiniotis
- 1] Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK [2] Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
| | - I Farrer
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - D A Ritchie
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - E Saitoh
- 1] Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan [2] The Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan [3] CREST, Japan Science and Technology Agency, Sanbancho, Tokyo 102-0075, Japan
| | - J Sinova
- 1] Institut fur Physik, Johannes Gutenberg-Universitat Mainz, 55128 Mainz, Germany [2] Institute of Physics ASCR v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - J Mašek
- Institute of Physics ASCR v.v.i., Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - 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
| | - C H W Barnes
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
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Uchida K, Ishida M, Kikkawa T, Kirihara A, Murakami T, Saitoh E. Longitudinal spin Seebeck effect: from fundamentals to applications. J Phys Condens Matter 2014; 26:343202. [PMID: 25105889 DOI: 10.1088/0953-8984/26/34/343202] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The spin Seebeck effect refers to the generation of spin voltage as a result of a temperature gradient in ferromagnetic or ferrimagnetic materials. When a conductor is attached to a magnet under a temperature gradient, the thermally generated spin voltage in the magnet injects a spin current into the conductor, which in turn produces electric voltage owing to the spin-orbit interaction. The spin Seebeck effect is of increasing importance in spintronics, since it enables direct generation of a spin current from heat and appears in a variety of magnets ranging from metals and semiconductors to insulators. Recent studies on the spin Seebeck effect have been conducted mainly in paramagnetic metal/ferrimagnetic insulator junction systems in the longitudinal configuration in which a spin current flowing parallel to the temperature gradient is measured. This 'longitudinal spin Seebeck effect' (LSSE) has been observed in various sample systems and exclusively established by separating the spin-current contribution from extrinsic artefacts, such as conventional thermoelectric and magnetic proximity effects. The LSSE in insulators also provides a novel and versatile pathway to thermoelectric generation in combination of the inverse spin-Hall effects. In this paper, we review basic experiments on the LSSE and discuss its potential thermoelectric applications with several demonstrations.
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Affiliation(s)
- K Uchida
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan. PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
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27
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An T, Vasyuchka VI, Uchida K, Chumak AV, Yamaguchi K, Harii K, Ohe J, Jungfleisch MB, Kajiwara Y, Adachi H, Hillebrands B, Maekawa S, Saitoh E. Unidirectional spin-wave heat conveyer. Nat Mater 2013; 12:549-553. [PMID: 23603850 DOI: 10.1038/nmat3628] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 03/12/2013] [Indexed: 06/02/2023]
Abstract
When energy is introduced into a region of matter, it heats up and the local temperature increases. This energy spontaneously diffuses away from the heated region. In general, heat should flow from warmer to cooler regions and it is not possible to externally change the direction of heat conduction. Here we show a magnetically controllable heat flow caused by a spin-wave current. The direction of the flow can be switched by applying a magnetic field. When microwave energy is applied to a region of ferrimagnetic Y3Fe5O12, an end of the magnet far from this region is found to be heated in a controlled manner and a negative temperature gradient towards it is formed. This is due to unidirectional energy transfer by the excitation of spin-wave modes without time-reversal symmetry and to the conversion of spin waves into heat. When a Y3Fe5O12 film with low damping coefficients is used, spin waves are observed to emit heat at the sample end up to 10 mm away from the excitation source. The magnetically controlled remote heating we observe is directly applicable to the fabrication of a heat-flow controller.
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Affiliation(s)
- T An
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
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28
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Nakayama H, Althammer M, Chen YT, Uchida K, Kajiwara Y, Kikuchi D, Ohtani T, Geprägs S, Opel M, Takahashi S, Gross R, Bauer GEW, Goennenwein STB, Saitoh E. Spin Hall magnetoresistance induced by a nonequilibrium proximity effect. Phys Rev Lett 2013; 110:206601. [PMID: 25167435 DOI: 10.1103/physrevb.87.144411] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Indexed: 05/27/2023]
Abstract
We report anisotropic magnetoresistance in Pt|Y(3)Fe(5)O(12) bilayers. In spite of Y(3)Fe(5)O(12) being a very good electrical insulator, the resistance of the Pt layer reflects its magnetization direction. The effect persists even when a Cu layer is inserted between Pt and Y(3)Fe(5)O(12), excluding the contribution of induced equilibrium magnetization at the interface. Instead, we show that the effect originates from concerted actions of the direct and inverse spin Hall effects and therefore call it "spin Hall magnetoresistance."
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Affiliation(s)
- H Nakayama
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - M Althammer
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany and Center for Materials Information Technology MINT and Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | - Y-T Chen
- Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - K Uchida
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Y Kajiwara
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - D Kikuchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Ohtani
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Geprägs
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - M Opel
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - S Takahashi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - R Gross
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany and Physik-Department, Technische Universität München, 85748 Garching, Germany
| | - G E W Bauer
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, The Netherlands and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S T B Goennenwein
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan and The Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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29
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Nakayama H, Althammer M, Chen YT, Uchida K, Kajiwara Y, Kikuchi D, Ohtani T, Geprägs S, Opel M, Takahashi S, Gross R, Bauer GEW, Goennenwein STB, Saitoh E. Spin Hall magnetoresistance induced by a nonequilibrium proximity effect. Phys Rev Lett 2013; 110:206601. [PMID: 25167435 DOI: 10.1103/physrevlett.110.206601] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Indexed: 06/03/2023]
Abstract
We report anisotropic magnetoresistance in Pt|Y(3)Fe(5)O(12) bilayers. In spite of Y(3)Fe(5)O(12) being a very good electrical insulator, the resistance of the Pt layer reflects its magnetization direction. The effect persists even when a Cu layer is inserted between Pt and Y(3)Fe(5)O(12), excluding the contribution of induced equilibrium magnetization at the interface. Instead, we show that the effect originates from concerted actions of the direct and inverse spin Hall effects and therefore call it "spin Hall magnetoresistance."
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Affiliation(s)
- H Nakayama
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - M Althammer
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany and Center for Materials Information Technology MINT and Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487, USA
| | - Y-T Chen
- Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - K Uchida
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Y Kajiwara
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - D Kikuchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - T Ohtani
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S Geprägs
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - M Opel
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - S Takahashi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - R Gross
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany and Physik-Department, Technische Universität München, 85748 Garching, Germany
| | - G E W Bauer
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, The Netherlands and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - S T B Goennenwein
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
| | - E Saitoh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan and CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan and The Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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Kikkawa T, Uchida K, Shiomi Y, Qiu Z, Hou D, Tian D, Nakayama H, Jin XF, Saitoh E. Longitudinal spin Seebeck effect free from the proximity Nernst effect. Phys Rev Lett 2013; 110:067207. [PMID: 23432302 DOI: 10.1103/physrevlett.110.067207] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Indexed: 06/01/2023]
Abstract
This Letter provides evidence for intrinsic longitudinal spin Seebeck effects (LSSEs) that are free from the anomalous Nernst effect (ANE) caused by an extrinsic proximity effect. We report the observation of LSSEs in Au/Y(3)Fe(5)O(12) (YIG) and Pt/Cu/YIG systems, showing that the LSSE appears even when the mechanism of the proximity ANE is clearly removed. In the conventional Pt/YIG structure, furthermore, we separate the LSSE from the ANE by comparing the voltages in different magnetization and temperature-gradient configurations; the ANE contamination was found to be negligibly small even in the Pt/YIG structure.
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Affiliation(s)
- T Kikkawa
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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31
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Abstract
Spin pumping driven by bistable exchange spin waves is demonstrated in a Pt/Y3Fe5O12 film under parametric excitation. In the Pt/Y3Fe5O12 film, the spin pumping driven by parametric excitation selectively enhances the relaxation of short-wavelength exchange spin waves, indicating strong coupling between the exchange spin waves and spin currents at the interface through efficient spin transfer. The parametric spin pumping, furthermore, allows direct access to nonlinear spin wave dynamics in combination with the inverse spin Hall effect, revealing unconventional bistability of the exchange spin waves.
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Affiliation(s)
- K Ando
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
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32
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Yamane Y, Sasage K, An T, Harii K, Ohe J, Ieda J, Barnes SE, Saitoh E, Maekawa S. Continuous generation of spinmotive force in a patterned ferromagnetic film. Phys Rev Lett 2011; 107:236602. [PMID: 22182112 DOI: 10.1103/physrevlett.107.236602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Indexed: 05/31/2023]
Abstract
We study, both experimentally and theoretically, the generation of a dc spinmotive force. By exciting a ferromagnetic resonance of a comb-shaped ferromagnetic thin film, a continuous spinmotive force is generated. Experimental results are well reproduced by theoretical calculations, offering a quantitative and microscopic understanding of this spinmotive force.
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Affiliation(s)
- Y Yamane
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.
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33
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Uchida K, Adachi H, An T, Ota T, Toda M, Hillebrands B, Maekawa S, Saitoh E. Long-range spin Seebeck effect and acoustic spin pumping. Nat Mater 2011; 10:737-741. [PMID: 21857673 DOI: 10.1038/nmat3099] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 07/13/2011] [Indexed: 05/31/2023]
Abstract
Imagine that a metallic wire is attached to a part of a large insulator, which itself exhibits no magnetization. It seems impossible for electrons in the wire to register where the wire is positioned on the insulator. Here we found that, using a Ni₈₁Fe₁₉/Pt bilayer wire on an insulating sapphire plate, electrons in the wire recognize their position on the sapphire. Under a temperature gradient in the sapphire, surprisingly, the voltage generated in the Pt layer is shown to reflect the wire position, although the wire is isolated both electrically and magnetically. This non-local voltage is due to the coupling of spins and phonons: the only possible carrier of information in this system. We demonstrate this coupling by directly injecting sound waves, which realizes the acoustic spin pumping. Our finding provides a persuasive answer to the long-range nature of the spin Seebeck effect, and it opens the door to 'acoustic spintronics' in which sound waves are exploited for constructing spin-based devices.
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Ando K, Takahashi S, Ieda J, Kurebayashi H, Trypiniotis T, Barnes CHW, Maekawa S, Saitoh E. Electrically tunable spin injector free from the impedance mismatch problem. Nat Mater 2011; 10:655-9. [PMID: 21706009 DOI: 10.1038/nmat3052] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 05/23/2011] [Indexed: 05/21/2023]
Abstract
Injection of spin currents into solids is crucial for exploring spin physics and spintronics. There has been significant progress in recent years in spin injection into high-resistivity materials, for example, semiconductors and organic materials, which uses tunnel barriers to circumvent the impedance mismatch problem; the impedance mismatch between ferromagnetic metals and high-resistivity materials drastically limits the spin-injection efficiency. However, because of this problem, there is no route for spin injection into these materials through low-resistivity interfaces, that is, Ohmic contacts, even though this promises an easy and versatile pathway for spin injection without the need for growing high-quality tunnel barriers. Here we show experimental evidence that spin pumping enables spin injection free from this condition; room-temperature spin injection into GaAs from Ni(81)Fe(19) through an Ohmic contact is demonstrated through dynamical spin exchange. Furthermore, we demonstrate that this exchange can be controlled electrically by applying a bias voltage across a Ni(81)Fe(19)/GaAs interface, enabling electric tuning of the spin-pumping efficiency.
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35
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Sandweg CW, Kajiwara Y, Chumak AV, Serga AA, Vasyuchka VI, Jungfleisch MB, Saitoh E, Hillebrands B. Spin pumping by parametrically excited exchange magnons. Phys Rev Lett 2011; 106:216601. [PMID: 21699324 DOI: 10.1103/physrevlett.106.216601] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Indexed: 05/31/2023]
Abstract
We experimentally show that exchange magnons can be detected by using a combination of spin pumping and the inverse spin-Hall effect proving its wavelength integrating capability down to the submicrometer scale. The magnons were injected in a ferrite yttrium iron garnet film by parametric pumping and the inverse spin-Hall effect voltage was detected in an attached Pt layer. The role of the density, wavelength, and spatial localization of the magnons for the spin pumping efficiency is revealed.
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Affiliation(s)
- C W Sandweg
- Fachbereich Physik and Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany.
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36
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Komiyama S, Aoki D, Saitoh E, Komiyama M, Udagawa Y. Biological significance of plasminogen activator inhibitor-1 expression in ovarian clear cell adenocarcinoma. EUR J GYNAECOL ONCOL 2011; 32:611-614. [PMID: 22335020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PURPOSE Ovarian clear cell adenocarcinoma (OCCA) has been reported to display different characteristics from other histological types of epithelial ovarian cancer, and especially differs from serous adenocarcinoma. We investigated plasminogen activator inhibitor-1 (PAI-1) expression in patients with OCCA and attempted to assess its biological significance. METHODS Fifty-seven patients with OCCA were enrolled. We used formalin-fixed, paraffin-embedded sections of the primary tumor obtained at the first operation to investigate the immunohistochemical expression of PAI-1 and the association of PAI-1 expression with various clinicopathologic factors. RESULTS The 57 patients were classified into a high PAI-1 expression group and a low expression group. Comparison between the two groups revealed that the percentage of patients with concomitant endometriosis was significantly larger in the high expression group, while the percentage of Stage I patients with positive peritoneal cytology was significantly larger in the low expression group. Comparison of cumulative 5-year survival rates showed that the high expression group had a better prognosis than the low expression group. CONCLUSION These data suggest an association between concomitant endometriosis and increased expression of PAI-1 in OCCA. The data also suggest that PAI-1 expression influences both peritoneal dissemination of early OCCA and the prognosis.
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Affiliation(s)
- S Komiyama
- Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Aichi, Japan.
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37
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Uchida K, Xiao J, Adachi H, Ohe J, Takahashi S, Ieda J, Ota T, Kajiwara Y, Umezawa H, Kawai H, Bauer GEW, Maekawa S, Saitoh E. Spin Seebeck insulator. Nat Mater 2010; 9:894-897. [PMID: 20871606 DOI: 10.1038/nmat2856] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 08/12/2010] [Indexed: 05/29/2023]
Abstract
Thermoelectric generation is an essential function in future energy-saving technologies. However, it has so far been an exclusive feature of electric conductors, a situation which limits its application; conduction electrons are often problematic in the thermal design of devices. Here we report electric voltage generation from heat flowing in an insulator. We reveal that, despite the absence of conduction electrons, the magnetic insulator LaY(2)Fe(5)O(12) can convert a heat flow into a spin voltage. Attached Pt films can then transform this spin voltage into an electric voltage as a result of the inverse spin Hall effect. The experimental results require us to introduce a thermally activated interface spin exchange between LaY(2)Fe(5)O(12) and Pt. Our findings extend the range of potential materials for thermoelectric applications and provide a crucial piece of information for understanding the physics of the spin Seebeck effect.
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38
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Ozaki K, Saitoh E, Kagaya H, Kondo I, Ozaki S, Itoh N, Ohashi A, Sutoh T. P26-5 Quantitative measure of hemiplegic upper limb by using three-dimensional motion analysis. Clin Neurophysiol 2010. [DOI: 10.1016/s1388-2457(10)61054-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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39
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Nakayama H, Ando K, Harii K, Kajiwara Y, Yoshino T, Uchida K, Ota T, Saitoh E. Detection of inverse spin-Hall effect induced in Pt1−xMx(M= Cu, Au) thin films. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/200/6/062014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Uchida K, Takahashi S, Harii K, Ieda J, Koshibae W, Ando K, Maekawa S, Saitoh E. Observation of the spin Seebeck effect. Nature 2008; 455:778-81. [PMID: 18843364 DOI: 10.1038/nature07321] [Citation(s) in RCA: 385] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Accepted: 08/04/2008] [Indexed: 11/09/2022]
Abstract
The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be exploited, for example, in thermal electric-power generators and for temperature sensing, by connecting two conductors with different Seebeck coefficients, a device called a thermocouple. Here we report the observation of the thermal generation of driving power, or voltage, for electron spin: the spin Seebeck effect. Using a recently developed spin-detection technique that involves the spin Hall effect, we measure the spin voltage generated from a temperature gradient in a metallic magnet. This thermally induced spin voltage persists even at distances far from the sample ends, and spins can be extracted from every position on the magnet simply by attaching a metal. The spin Seebeck effect observed here is directly applicable to the production of spin-voltage generators, which are crucial for driving spintronic devices. The spin Seebeck effect allows us to pass a pure spin current, a flow of electron spins without electric currents, over a long distance. These innovative capabilities will invigorate spintronics research.
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Affiliation(s)
- K Uchida
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
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Ando K, Takahashi S, Harii K, Sasage K, Ieda J, Maekawa S, Saitoh E. Electric manipulation of spin relaxation using the spin Hall effect. Phys Rev Lett 2008; 101:036601. [PMID: 18764271 DOI: 10.1103/physrevlett.101.036601] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Indexed: 05/26/2023]
Abstract
Using the spin Hall effect, magnetization relaxation in a Ni_{81}Fe_{19}/Pt film is manipulated electrically. An electric current applied to the Pt layer exerts spin torque on the entire magnetization of the Ni81Fe19 layer via the macroscopic spin transfer induced by the spin Hall effect and modulates the magnetization relaxation in the Ni81Fe19 layer. This method allows us to tune the magnetization dynamics regardless of the film size without applying electric currents directly to the magnetic layer.
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Affiliation(s)
- K Ando
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan.
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Muraoka Y, Saitoh E, Otsuka K, Ito N, Aoki T, Yamagami J, Fujino H, Kagawa T. Treadmill gait analysis 1: Extraction of gait pattern components from Lissajous figure by FFT smoother. Clin Neurophysiol 2007. [DOI: 10.1016/j.clinph.2007.05.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Suzuki T, Sonoda S, Saitoh E, Onogi K, Fujino H, Teranishi T, Oyobe T, Katoh M, Ohtsuka K. Prediction of gait outcome with the knee-ankle-foot orthosis with medial hip joint in patients with spinal cord injuries: a study using recursive partitioning analysis. Spinal Cord 2006; 45:57-63. [PMID: 16819556 DOI: 10.1038/sj.sc.3101955] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Retrospective study of the degree of gait independence achieved by persons with spinal cord injury (SCI) using knee-ankle-foot orthosis with a medial single hip joint (MSH-KAFO). OBJECTIVE To examine the effects of the neurological level, degree of paresis, age, and inhibitory physical/other factors on the gait with a MSH-KAFO in patients with SCIs. SETTING Three university hospitals and two rehabilitation hospitals in Japan. METHODS The 45 patients (36 men, nine women) examined included 10 with injuries in the cervical cord between C6 and C8 (group C), 20 with injuries in the upper-middle thoracic cord between T4 and T10 (group UT), and 15 with injuries in the lower thoracic-lumbar cord between T12 and L1 (group TL). Mean age was 34.0 years (range 16-68 years). Of these patients, 13 used the Walkabout, four used the gear joint, and 28 used the Primewalk as the medial hip joint. Recursive partitioning, which predicted the final status of gait from the level, degree of paresis, age, and inhibitory factors, was performed, and a decision tree for gait was constructed. Inhibitory factors were spasticity, involuntary spasms or muscle contractions, pain, contracture, weakness of the upper extremities, and decreased motivation to perform gait exercise. The degree of gait independence was rated on the following five-point scale: outdoor independent gait (5 points), indoor independent gait (4 points), indoor supervised gait (3 points), indoor assisted gait (2 points), and gait within parallel bars (1 point). New branches were added to the decision tree for gait based on the clinical experience, thereby constructing a new decision tree. RESULTS The coincident ratio between the value predicted on the basis of the decision tree of gait and the value actually observed was 53.3%. The coincident ratio between the value predicted on the basis of the modified decision tree of gait and the actually observed value was 68.9%. CONCLUSION The results provide valuable information to medical teams that may assist prescription of gait orthoses.
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Affiliation(s)
- T Suzuki
- Nanakuri Sanatorium, Fujita Health University, 424-1 Ohdori-cho, Tsu-city, Mie 514-1295, Japan
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Abstract
Gefitinib is a potent drug used in the treatment of nonsmall-cell lung cancer (NSCLC). Gefitinib acts by inhibition of the epidermal growth factor receptor tyrosine kinase. Clinical trials have confirmed the efficacy of gefitinib for NSCLC. Adverse drug reactions, although frequent, are mild, and include acne-like skin rash and diarrhoea. The present study describes the case of a 56-yr-old male with NSCLC who, 4 weeks after treatment with gefitinib, suffered from a severe alveolar haemorrhage diagnosed by bronchoalveolar lavage. This is the first case report of an acute life-threatening lung injury in a patient with nonsmall-cell lung cancer who had been given gefitinib.
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Affiliation(s)
- R Ieki
- Metropolitan Komagome Hospital, Internal Medicine, Tokyo, Japan.
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Suzuki T, Saitoh E, Daikuya S, Hirose H, Tani M, Nabeta R, Wakayama I, Fujiwara T. Characteristics of F-wave in different stretched positions of the affected arm in patients with cerebrovascular diseases. Electromyogr Clin Neurophysiol 2003; 43:97-101. [PMID: 12661134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
To investigate the effect of continued stretching of affected arms in patients with cerebrovascular disease (CVD), F-wave was tested from the abductor pollicis brevis (APB) during relaxation (trial 1) and 3 different continued stretches: stretched position with shoulder abduction (trial 2), stretched position with shoulder abduction and elbow extension (trial 3), and stretched position with shoulder abduction, elbow extension and wrist extension (trial 4) of the affected arm for 1 min. in 20 hemiparesis patients with moderate hypertonus (modified Ashworth scale of 2 or 3) caused by CVD (mean age of 49.5 years). Persistence and amplitude ratio of F/M in trial 2 were the same as those in trial 1. Persistence and amplitude ratio of F/M in trials 3 and 4 were significantly lower than those in trial 1. It was suggested that excitability of spinal neural function of the distal part, the APB, of the affected arm was reduced during continued stretching of the proximal part, shoulder and elbow joints, or all of the shoulder, elbow and wrist joints in hemiparesis patients with moderate hypertonus caused by CVD.
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Affiliation(s)
- T Suzuki
- Research Center of Neurological Diseases, Kansai College of Oriental Medicine.
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Suzuki T, Saitoh E, Tani M, Nabeta R, Daikuya S, Hirose H, Wakayama I, Fujiwara T. Effect of continued stretching of the affected arm in patients with cerebrovascular diseases by examining H-reflex characteristics. Electromyogr Clin Neurophysiol 2003; 43:51-6. [PMID: 12613141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
To investigate excitability of spinal neural function during stretching excises in patients with cerebrovascular disease (CVD), H-reflex was analyzed before, during and after 1 min. continued stretching of the affected arm. 10 hemiparesis patients with hypertonus and hyperreflex, mean age of 53.2 years were tested. H-reflex was recorded from the abductor pollicis brevis on the affected side after stimulation of median nerve in supine position. The persistence, amplitude and amplitude ratio of H/M during stretching were lower than those before and after in the patients with moderately increased muscle tonus. In patients with slightly and markedly increased, H-reflex was same before, during and after continued stretching. It is suggested that excitability of spinal neural function during 1 min. continued stretching was inhibited in the patients with moderately increased muscle tonus caused by CVD.
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Affiliation(s)
- T Suzuki
- Research Center of Neurological Diseases, Kansai College of Oriental Medicine.
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Suzuki T, Saitoh E, Tani M, Nabeta R, Daikuya S, Hirose H, Wakayama I, Fujiwara T. Characteristic appearances of the H-reflex and F-wave with increased stimulus intensity in patients with cerebrovascular disease. Electromyogr Clin Neurophysiol 2002; 42:67-70. [PMID: 11938596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
We experienced H-reflex may be evoked with supramaximal stimulation in patients with cerebrovascular disease (CVD). In this study, we investigated the relationship between the characteristic appearances of H-reflex and F-wave with increased stimulus intensity and neurological signs. We examined the H-reflex and F-wave of the affected arm with increased stimulus intensity during muscle relaxation in 31 patients (17 males and 14 females) with hemiparesis caused by CVD. Mean patient age was 56.0 (range 30-82) years. 30 healthy subjects, mean age of 56.2 (range 28-80) were investigated using the same method as controlled group. H-reflex and F-wave with increased stimulus intensity after the median nerve stimulation at the wrist were recorded from the opponence pollicis muscle on the affected side in patients with CVD or right arm in the healthy subjects. Appearance patterns of the H-reflex and F-wave with increased stimulus intensity was separated into four types. Type 1: F-wave appeared with increased stimulus intensity, but there was no H-reflex. Type 2: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave followed disappearance of the H-reflex with increased stimulus intensity. Type 3: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave appeared during the H-reflex with increased stimulus intensity. Type 4: Only the H-reflex appeared with increased stimulus intensity, but there was no F-wave. Neurological findings including muscle tone and tendon reflex were also evaluated. Findings on muscle tone and tendon reflex were classified into increased (markedly, moderately and slightly), normal and decreased. Results were analyzed as follows; 1) The characteristic appearances of H-reflex and F-wave in the healthy subjects and 2) The relationship between characteristic appearances of waves with increased stimulus intensity and neurological signs in patients with CVD. 1) Pattern of the H-reflex and F-wave with increased stimulus intensity in all healthy subjects were type 1. 2) Patterns of the H-reflex and F-wave with increased stimulus intensity in patients with markedly increased muscle tone and tendon reflex were almost always type 4. Those with moderately increased signs in this parameter demonstrated type 2 or 3. Those with slightly increased signs in this parameter demonstrated type 1 or 2. Those with normal or decreased signs were type 1. These findings suggest that the characteristic appearances of the H-reflex and F-wave was influenced by grade of neurological signs.
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Affiliation(s)
- T Suzuki
- Research Center of Neurological Diseases, Kansai College of Oriental Medicine.
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Saitoh E, Okamoto S, Takahashi KT, Tobe K, Yamamoto K, Kimura T, Ishihara S, Maekawa S, Tokura Y. Observation of orbital waves as elementary excitations in a solid. Nature 2001; 410:180-3. [PMID: 11242071 DOI: 10.1038/35065547] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A basic concept in solid-state physics is that when some kind of symmetry in a solid is spontaneously broken, collective excitations will arise. For example, phonons are the collective excitations corresponding to lattice vibrations in a crystal, and magnons correspond to spin waves in a magnetically ordered compound. Modulations in the relative shape of the electronic clouds in an orbitally ordered state could in principle give rise to orbital waves, or 'orbitons', but this type of elementary excitation has yet to be observed experimentally. Systems in which the electrons are strongly correlated-such as high-temperature superconductors and manganites exhibiting colossal magnetoresistivity-are promising candidates for supporting orbital waves, because they contain transition-metal ions in which the orbital degree of freedom is important. Orbitally ordered states have been found in several transition-metal compounds, and orbitons have been predicted theoretically for LaMnO3. Here we report experimental evidence for orbitons in LaMnO3, using Raman scattering measurements. We perform a model calculation of orbiton resonances which provides a good fit to the experimental data.
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Affiliation(s)
- E Saitoh
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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Abstract
PURPOSE To verify the efficiency and objectivity of the pattern visual evoked potential (VEP) for organic disorders of the cortical visual system. METHODS This retrospective study evaluated VEP in 19 patients diagnosed with psychogenic visual disturbance, 7 patients with malingering, and 37 age-matched normal volunteers. Transient (3 reversals per second) and steady-state (12 reversals per second) pattern VEPs for check sizes 15' and 30', with a contrast of 80%, were recorded. RESULTS The amplitudes of both transient and steady-state pattern VEPs were significantly increased in patients with psychogenic visual disturbance, while patients with malingering had significantly lower amplitudes. P100 peak latency was prolonged in both groups of patients. CONCLUSION Monitoring of patients' fixation on the stimulus showed those with psychogenic visual disturbance fixated well on the stimulus, while those with malingering did not. This finding produced a VEP amplitude reduction in patients with malingering. The reason for the VEP amplitude in patients with psychogenic visual disturbance is unclear.
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Affiliation(s)
- E Saitoh
- Department of Ophthalmology, Chiba University School of Medicine, Japan
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Abstract
Cystatins are physiological cysteine proteinase inhibitors. Here we report a novel function for some family 2 cystatins that is not related to these activities. The release of interleukin-6 (IL-6) and interleukin-8 (IL-8) by the gingival fibroblasts and that of IL-6 by murine splenocytes were measured using ELISA systems specific for these cytokine molecules. Family 2 cystatins, including cystatins C, SA1, SA2, S, and egg white cystatin, upregulated the IL-6 production by two-lasts at physiological concentrations. After complete saturation with papain, those family 2 cystatins still upregulated IL-6 production, suggesting that the papain-inhibitory site was not involved in the cytokine-inducing activity.
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Affiliation(s)
- T Kato
- Department of Microbiology, Tokyo Dental College, Chiba, Japan
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