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Journal Articles

Internal residual stress evaluation of bearing balls for automobile parts

Miyakawa, Susumu*; Ito, Toshimasa*; Iwahori, Keisuke*; Aoyama, Yoshihiko*; Kubo, Ryosuke*; Murata, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Kajiwara, Kentaro*

Zairyo, 69(4), p.308 - 314, 2020/04

White etching area which looks white with nital corrosive liquid may be recognized at the flaking part of a rolling bearing on which high contact stress of several GPa is applied repeatedly. Up to now, studies of white etching area of a ball have been less than studies of white etching area of inner and outer rings. In this study, as part of the flaking mechanism explication with white etching area of a ball, internal residual stress distributions of ball by using high energy white X-ray of SPring-8 (A method) and laboratorial X-ray measurement equipment (B method) were investigated. The former was modified by surface residual stress according to B method. The latter was modified by releasing stress in the form of electrolytic polishing. The results showed modified residual stress distributions almost agree qualitatively.

JAEA Reports

Development of ITER CODAC compatible gyrotron local control system and its operation

Oshima, Katsumi; Oda, Yasuhisa; Takahashi, Koji; Terakado, Masayuki; Ikeda, Ryosuke; Hayashi, Kazuo*; Moriyama, Shinichi; Kajiwara, Ken; Sakamoto, Keishi

JAEA-Technology 2015-061, 65 Pages, 2016/03


In JAEA, an ITER relevant control system for ITER gyrotron was developed according to Plant Control Design Handbook. This control system was developed based on ITER CODAC Core System and implemented state machine control of gyrotron operation system, sequential timing control of gyrotron oscillation startup, and data acquisition. The operation of ITER 170 GHz gyrotron was demonstrated with ITER relevant power supply configuration. This system is utilized for gyrotron operation test for ITER procurement. This report describes the architecture of gyrotron operation system, its basic and detailed design, and recent operation results.

Journal Articles

Spin-electricity conversion induced by spin injection into topological insulators

Shiomi, Yuki*; Nomura, Kentaro*; Kajiwara, Yosuke*; Eto, Kazuma*; Novak, M.*; Segawa, Koji*; Ando, Yoichi*; Saito, Eiji

Physical Review Letters, 113(19), p.196601_1 - 196601_5, 2014/11

 Times Cited Count:217 Percentile:99.13(Physics, Multidisciplinary)

Journal Articles

Development of ITER CODAC compatible gyrotron local control system and its operation

Oda, Yasuhisa; Oshima, Katsumi; Nakamoto, Takashi*; Hashimoto, Yasunori*; Yamamoto, Tsuyoshi; Hayashi, Kazuo*; Ikeda, Yukiharu; Ikeda, Ryosuke; Kajiwara, Ken; Takahashi, Koji; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 90(7), p.365 - 373, 2014/07

no abstracts in English

Journal Articles

Spin-wave spin current in magnetic insulators

Uchida, Kenichi*; Adachi, Hiroto; Kajiwara, Yosuke*; Maekawa, Sadamichi; Saito, Eiji

Solid State Physics, 64; Recent Advances in Magnetic Insulators; From Spintronics to Microwave Applications, p.1 - 27, 2013/11

 Times Cited Count:7 Percentile:12.07(Physics, Condensed Matter)

Journal Articles

Spin mixing conductance at a well-controlled platinum/yttrium iron garnet interface

Qiu, Z.*; Ando, Kazuya*; Uchida, Kenichi*; Kajiwara, Yosuke*; Takahashi, Ryo*; Nakayama, Hiroyasu*; An, Toshu*; Fujikawa, Yasunori*; Saito, Eiji

Applied Physics Letters, 103(9), p.092404_1 - 092404_4, 2013/08

 Times Cited Count:97 Percentile:95.88(Physics, Applied)

A platinum (Pt)/yttrium iron garnet (YIG) bilayer system with a well-controlled interface has been developed; spin mixing conductance at the Pt/YIG interface has been studied. A clear interface with good crystal perfection is experimentally demonstrated to be one of the important factors for an ultimate spin mixing conductance. The spin mixing conductance is obtained to be 1.3$$times$$10$$^{18}$$m$$^{-2}$$ at the well-controlled Pt/YIG interface, which is close to a theoretical prediction.

Journal Articles

Spin-relaxation modulation and spin-pumping control by transverse spin-wave spin current in Y$$_3$$Fe$$_5$$O$$_{12}$$

Kajiwara, Yosuke*; Uchida, Kenichi*; Kikuchi, Daisuke*; An, Toshu*; Fujikawa, Yasunori*; Saito, Eiji

Applied Physics Letters, 103(5), p.052404_1 - 052404_4, 2013/07

 Times Cited Count:6 Percentile:30.5(Physics, Applied)

Heat-current-induced manipulation of spin relaxation in Y$$_3$$Fe$$_5$$O$$_{12}$$ under an in-plane temperature gradient is investigated. We show that the linewidth of the ferromagnetic resonance spectrum, i.e., the spin relaxation, in an Y$$_3$$Fe$$_5$$O$$_{12}$$ film increases or decreases depending on the temperature-gradient direction and that this modulation is attributed to the spin-transfer torque caused by a thermally induced transverse spin-wave spin current in the Y$$_3$$Fe$$_5$$O$$_{12}$$ film. The experimental results also show that the spin-current magnitude generated by spin pumping in an attached Pt film is inversely proportional to the square of the modulated Gilbert damping constant, consistent with a phenomenological spin-pumping model.

Journal Articles

Unidirectional spin-wave heat conveyer

An, Toshu*; Vasyuchka, V. I.*; Uchida, Kenichi*; Chumak, A. V.*; Yamaguchi, Kazuya*; Harii, Kazuya; Oe, Junichiro*; Jungfleisch, M. B.*; Kajiwara, Yosuke*; Adachi, Hiroto; et al.

Nature Materials, 12(6), p.549 - 553, 2013/06

 Times Cited Count:102 Percentile:96.17(Chemistry, Physical)

Journal Articles

Longitudinal spin Seebeck effect in various garnet ferrites

Uchida, Kenichi*; Nonaka, Tatsumi*; Kikkawa, Takashi*; Kajiwara, Yosuke*; Saito, Eiji

Physical Review B, 87(10), p.104412_1 - 104412_6, 2013/03

 Times Cited Count:83 Percentile:94.96(Materials Science, Multidisciplinary)

The longitudinal spin Seebeck effect (LSSE) is investigated in various garnet ferritesY$$_{3-x}$$$$R$$$$_{x}$$Fe$$_{5-y}$$$$M$$$$_{y}$$O$$_{12}$$ ($$R$$ = Gd, Ca; $$M$$ = Al, Mn, V, In, Zr) by means of the inverse spin Hall effect in Pt films. The magnitude of the LSSE voltage in the Pt/Y$$_{3-x}$$$$R$$$$_{x}$$Fe$$_{5-y}$$$$M$$$$_{y}$$O$$_{12}$$ samples is found to be enhanced with increasing concentration of Fe in the garnet ferrites, which can be explained by a change in the spin-mixing conductance at the Pt/Y$$_{3-x}$$$$R$$$$_{x}$$Fe$$_{5-y}$$$$M$$$$_{y}$$O$$_{12}$$ interfaces. We also investigate the dependence of the LSSE voltage on macroscopic magnetic parameters of Y$$_{3-x}$$$$R$$$$_{x}$$Fe$$_{5-y}$$$$M$$$$_{y}$$O$$_{12}$$. The experimental results show that the LSSE voltage in the Pt/Y$$_{3-x}$$$$R$$$$_{x}$$Fe$$_{5-y}$$$$M$$$$_{y}$$O$$_{12}$$ samples hasa positive correlation with the Curie temperature and the saturation magnetization, but no clear correlation with the gyromagnetic ratio and the Gilbert damping constant of the samples.

Journal Articles

Heat-induced damping modification in yttrium iron garnet/platinum hetero-structures

Jungfleisch, M. B.*; An, Toshu*; Ando, Kazuya*; Kajiwara, Yosuke*; Uchida, Kenichi*; Vasyuchka, V. I.*; Chumak, A. V.*; Serga, A. A.*; Saito, Eiji; Hillebrands, B.*

Applied Physics Letters, 102(6), p.062417_1 - 062417_4, 2013/02

 Times Cited Count:45 Percentile:88(Physics, Applied)

Journal Articles

Spin-current-driven thermoelectric coating

Kirihara, Akihiro*; Uchida, Kenichi*; Kajiwara, Yosuke*; Ishida, Masahiko*; Nakamura, Yasunobu*; Manako, Takashi*; Saito, Eiji; Yorozu, Shinichi*

Nature Materials, 11(8), p.686 - 689, 2012/08

 Times Cited Count:202 Percentile:98.62(Chemistry, Physical)

Journal Articles

Interface induced inverse spin Hall effect in bismuth/permalloy bilayer

Hou, D.*; Qiu, Z.*; Harii, Kazuya; Kajiwara, Yosuke*; Uchida, Kenichi*; Fujikawa, Yasunori*; Nakayama, Hiroyasu*; Yoshino, Tatsuro*; An, Toshu*; Ando, Kazuya*; et al.

Applied Physics Letters, 101(4), p.042403_1 - 042403_4, 2012/07

 Times Cited Count:60 Percentile:91.48(Physics, Applied)

Inverse spin Hall effect has been investigated in bismuth(Bi)/permalloy(Py) bilayer films by using the spin pumping at room temperature. From the ferromagnetic-resonance-spectrum linewidth data, Bi is proved to be a good spin sink in our structure. We measured inverse spin Hall voltage and conductance of the Bi/Py bilayer and found that the inverse spin Hall current, $$I_c$$, decreases with increasing the Bi thickness, which is in contrast to the former understanding in similar bilayer systems, e.g., Pt/Py. We constructed a model to explain the thickness dependence of $$I_c$$ quantitatively, in which spin transport modulation near Bi/Py interface is considered.

Journal Articles

Thermal spin pumping and magnon-phonon-mediated spin-Seebeck effect

Uchida, Kenichi*; Ota, Takeru*; Adachi, Hiroto; Xiao, J.*; Nonaka, Tatsumi*; Kajiwara, Yosuke*; Bauer, G. E. W.*; Maekawa, Sadamichi; Saito, Eiji

Journal of Applied Physics, 111(10), p.103903_1 - 103903_11, 2012/05

 Times Cited Count:106 Percentile:96.24(Physics, Applied)

Journal Articles

Geometry dependence on inverse spin Hall effect induced by spin pumping in Ni$$_{81}$$Fe$$_{19}$$/Pt films

Nakayama, Hiroyasu*; Ando, Kazuya*; Harii, Kazuya; Yoshino, Tatsuro*; Takahashi, Ryo*; Kajiwara, Yosuke*; Uchida, Kenichi*; Fujikawa, Yasunori*; Saito, Eiji

Physical Review B, 85(14), p.144408_1 - 144408_7, 2012/04

 Times Cited Count:161 Percentile:97.96(Materials Science, Multidisciplinary)

Geometric effects on the inverse spin Hall effect (ISHE) induced by the spin pumping driven by the ferromagnetic resonance (FMR) have been investigated quantitatively. We measured the FMR spectra and the electromotive force induced by the ISHE with changing the size and the thickness in Ni$$_{81}$$Fe$$_{19}$$/Pt films. The intensity of generated charge currents due to the ISHE changes systematically with changing the film geometry. The experimental results show a clear difference between Ni$$_{81}$$Fe$$_{19}$$ and Pt thickness dependence of the ISHE induced by the spin pumping.

Journal Articles

All-oxide system for spin pumping

Qiu, Z.*; Kajiwara, Yosuke*; Ando, Kazuya*; Fujikawa, Yasunori*; Uchida, Kenichi*; Tashiro, Takaharu*; Harii, Kazuya*; Yoshino, Tatsuro*; Saito, Eiji

Applied Physics Letters, 100(2), p.022402_1 - 022402_3, 2012/01

 Times Cited Count:28 Percentile:76.85(Physics, Applied)

In a simple all-oxide system, spin pumping driven by spin wave resonances have been investigated by using the inverse spin-Hall effect (ISHE). In a lanthanum doped yttrium iron garnet (La:YIG)/indium tin oxide (ITO) bilayer film, the spin pumping generates and injects a spin current into the ITO layer, and an electromotive force signal is observed via the ISHE. The electromotive forces were measured depend on the out-of-plane magnetic-field-angle and the microwave excitation power, which were consistent with the theoretical prediction of the ISHE. The realization of the all-oxide spin pumping system extends possibilities for the oxide spintronics.

Journal Articles

Surface-acoustic-wave-driven spin pumping in Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$/Pt hybrid structure

Uchida, Kenichi*; An, Toshu*; Kajiwara, Yosuke*; Toda, Masaya*; Saito, Eiji

Applied Physics Letters, 99(21), p.212501_1 - 212501_3, 2011/11

 Times Cited Count:41 Percentile:84.26(Physics, Applied)

A spin current generated from a surface acoustic wave (SAW) was observed in an Y$$_{3}$$Fe$$_{5}$$O$$_{12}$$/Pt(YIG)/Pt hybrid structure. At the YIG/Pt interface, a SAW generated in the YIG layer was found to pump a spin current into the Pt layer, which was detected through the inverse spin-Hall effect in the Pt. The YIG/Pt lateral structure combined with a piezoelectric wedge transducer enables the systematic investigation of the spin-voltage distribution due to the SAW in the YIG. Since the observed phenomenon has high affinity with SAW-based electronics, it will pave the way for constructing spintronic SAW devices.

Journal Articles

Detection of spin-wave spin current in a magnetic insulator

Kajiwara, Yosuke*; Takahashi, Saburo*; Maekawa, Sadamichi; Saito, Eiji*

IEEE Transactions on Magnetics, 47(6), p.1591 - 1594, 2011/06

 Times Cited Count:8 Percentile:47.07(Engineering, Electrical & Electronic)

Journal Articles

Inverse spin-Hall effect induced by spin pumping in metallic systems

Ando, Kazuya*; Takahashi, Saburo; Ieda, Junichi; Kajiwara, Yosuke*; Nakayama, Hiroyasu*; Yoshino, Tatsuro*; Harii, Kazuya*; Fujikawa, Yasunori*; Matsuo, Mamoru*; Maekawa, Sadamichi; et al.

Journal of Applied Physics, 109(10), p.103913_1 - 103913_11, 2011/05

 Times Cited Count:338 Percentile:99.43(Physics, Applied)

The inverse spin-Hall effect (ISHE) induced by the spin pumping has been investigated systematically in simple ferromagnetic/paramagnetic bilayer systems. The spin pumping driven by ferromagnetic resonance injects a spin current into the paramagnetic layer, which gives rise to an electromotive force transverse to the spin current using the ISHE in the paramagnetic layer. In a Ni$$_{81}$$Fe$$_{19}$$/Pt film, we found an electromotive force perpendicular to the applied magnetic field at the ferromagnetic resonance condition. The spectral shape of the electromotive force is well reproduced using a simple Lorentz function, indicating that the electromotive force is due entirely to the ISHE induced by the spin pumping; the extrinsic magnetogalvanic effects are eliminated in this measurement. The electromotive force varies systematically by changing the microwave power, magnetic-field angle, and film size, which are well reproduced by a calculation based on the Landau-Lifshitz-Gilbert equation combined with the models of the ISHE and spin pumping. The electromotive force was observed also in a Pt/Y$$_3$$Fe$$_4$$GaO$$_{12}$$ film, in which the metallic Ni$$_{81}$$Fe$$_{19}$$ layer is replaced by an insulating Y$$_3$$Fe$$_4$$GaO$$_{12}$$ layer, supporting that the spin-pumping-induced ISHE is responsible for the observed electromotive force.

Journal Articles

Spin pumping by parametrically excited exchange magnons

Sandweg, C. W.*; Kajiwara, Yosuke*; Chumak, A. V.*; Serga, A. A.*; Vasyuchka, V. I.*; Jungfleisch, M. B.*; Saito, Eiji; Hillebrands, B.*

Physical Review Letters, 106(21), p.216601_1 - 216601_4, 2011/05

 Times Cited Count:208 Percentile:98.46(Physics, Multidisciplinary)

Journal Articles

Universality of the spin pumping in metallic bilayer films

Yoshino, Tatsuro*; Ando, Kazuya*; Harii, Kazuya*; Nakayama, Hiroyasu*; Kajiwara, Yosuke*; Saito, Eiji

Applied Physics Letters, 98(3), p.132503_1 - 132503_3, 2011/03

 Times Cited Count:30 Percentile:77.86(Physics, Applied)

We show a clear guideline for generating a large spin current using the spin pumping in metallic bilayer films. We measured spin currents generated by the spin pumping in Ni$$_{1-x}$$Fe$$_{x}$$/Pt bilayer films using the inverse spin-Hall effect (ISHE). The magnitude of the ISHE signals are well reproduced by a calculation based on the model of the spin pumping. The result shows that the amplitude of a spin current is universally determined by the product of the saturation magnetization, the additional damping constant, and the solid angle of the magnetization precession.

46 (Records 1-20 displayed on this page)