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Jiang, N.*; Nii, Yoichi*; Arisawa, Hiroki*; Saito, Eiji; Oe, Junichiro*; Onose, Yoshinori*
Physical Review Letters, 126(17), p.177205_1 - 177205_5, 2021/04
Times Cited Count：2 Percentile：36.98(Physics, Multidisciplinary)
Fe
O
as the origin of low-magnetic-field behavior of the spin Seebeck effectUchida, Kenichi*; Oe, Junichiro*; Kikkawa, Takashi*; Daimon, Shunsuke*; Hou, D.*; Qiu, Z.*; Saito, Eiji
Physical Review B, 92(1), p.014415_1 - 014415_8, 2015/07
Times Cited Count：33 Percentile：79.02(Materials Science, Multidisciplinary)
OSeO
Hirobe, Daichi*; Shiomi, Yuki*; Shimada, Yuki*; Oe, Junichiro*; Saito, Eiji
Journal of Applied Physics, 117(5), p.053904_1 - 053904_6, 2015/02
Times Cited Count：9 Percentile：39.38(Physics, Applied)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：122 Percentile：96.28(Chemistry, Physical)Tanabe, Kenji*; Chiba, Daichi*; Oe, Junichiro*; Kasai, Shinya*; Kono, Hideo*; Barnes, S. E.*; Maekawa, Sadamichi; Kobayashi, Kensuke*; Ono, Teruo*
Nature Communications (Internet), 3, p.845_1 - 845_5, 2012/05
Times Cited Count：41 Percentile：82.99(Multidisciplinary Sciences)Hayashi, Masamitsu*; Ieda, Junichi; Yamane, Yuta; Oe, Junichiro*; Takahashi, Yukiko*; Mitani, Seiji*; Maekawa, Sadamichi
Physical Review Letters, 108(14), p.147202_1 - 147202_5, 2012/04
Times Cited Count：37 Percentile：82.69(Physics, Multidisciplinary)Spinmotive force associated with a moving domain wall is observed directly in permalloy nanowires using real time voltage measurements with proper subtraction of the electromotive force. Whereas the wall velocity exhibits nonlinear dependence on a magnetic field, the generated voltage increases linearly with the field. We show that the sign of the voltage reverses when the wall propagation direction is altered. Numerical simulations explain quantitatively these features of spinmotive force and indicate that the spinmotive force scales with the field even in a field range where the wall motion is no longer associated with periodic structure transformation.
Yamane, Yuta; Sasage, Kohei*; An, Toshu*; Harii, Kazuya*; Oe, Junichiro*; Ieda, Junichi; Barnes, S. E.*; Saito, Eiji; Maekawa, Sadamichi
Physical Review Letters, 107(23), p.236602_1 - 236602_4, 2011/11
Times Cited Count：45 Percentile：85.75(Physics, Multidisciplinary)Yamane, Yuta; Ieda, Junichi; Oe, Junichiro*; Barnes, S. E.*; Maekawa, Sadamichi
Applied Physics Express, 4(9), p.093003_1 - 093003_3, 2011/09
Times Cited Count：9 Percentile：38.64(Physics, Applied)Yamane, Yuta; Ieda, Junichi; Oe, Junichiro*; Barnes, S. E.*; Maekawa, Sadamichi
Journal of Applied Physics, 109(7), p.07C735_1 - 07C735_3, 2011/04
Times Cited Count：19 Percentile：62.07(Physics, Applied)Oe, Junichiro; Adachi, Hiroto; Takahashi, Saburo; Maekawa, Sadamichi
Physical Review B, 83(11), p.115118_1 - 115118_5, 2011/03
Times Cited Count：46 Percentile：84.44(Materials Science, Multidisciplinary)Thermally driven spin-wave spin currents in ferromagnetic (FM) materials and a resulting measurable electric signal in a normal metal (NM) probe placed on FM are theoretically investigated. We develop the numerical technique for calculating a spin Seebeck signal detected by the NM probe that converts the spin current to the charge current. By taking into account the fluctuation-dissipation theorem for thermally fluctuating spins at the interface of a FM/NM junction, the spin current is induced in the NM probe via an exchange interaction when the FM feels the temperature gradient. Numerical simulation clarifies the role of the sample boundary on the spatial distribution of the spin current both in FM and NM. The spin-wave spin current that flows parallel to the heat current is also investigated.
Adachi, Hiroto; Oe, Junichiro; Takahashi, Saburo; Maekawa, Sadamichi
Physical Review B, 83(9), p.094410_1 - 094410_6, 2011/03
Times Cited Count：230 Percentile：98.58(Materials Science, Multidisciplinary)We formulate a linear response theory of the spin Seebeck effect, i.e., a spin voltage generation from heat current flowing in a ferromagnet. Our approach focuses on the collective magnetic excitation of spins, i.e., magnons. We show that the linear-response formulation provides us with a qualitative as well as quantitative understanding of the spin Seebeck effect observed in a prototypical magnet, yttrium iron garnet.
Adachi, Hiroto; Uchida, Kenichi*; Saito, Eiji; Oe, Junichiro; Takahashi, Saburo; Maekawa, Sadamichi
Applied Physics Letters, 97(25), p.252506_1 - 252506_3, 2010/12
Times Cited Count：140 Percentile：96.54(Physics, Applied)We investigate both theoretically and experimentally a gigantic enhancement of the spin Seebeck effect in a prototypical magnet LaY
FeO at low temperatures. Our theoretical analysis sheds light on the important role of phonons: the spin Seebeck effect is enormously enhanced by nonequilibrium phonons that drag low-lying spin excitations. We further argue that this scenario gives a clue to understand the observation of the spin Seebeck effect that is unaccompanied by a global spin current, and predict that the substrate condition affects the observed signal.
Uchida, Kenichi*; Xiao, J.*; Adachi, Hiroto; Oe, Junichiro; Takahashi, Saburo; Ieda, Junichi; Ota, Takeru*; Kajiwara, Yosuke*; Umezawa, Hiromitsu*; Kawai, Hirotaka*; et al.
Nature Materials, 9(11), p.894 - 897, 2010/11
Times Cited Count：1023 Percentile：99.88(Chemistry, Physical)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 LaYFeO 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 result require us to introduce a thermally activated interface spin exchange between LaYFeO 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.
Oe, Junichiro; Gu, B.; Maekawa, Sadamichi
Kotai Butsuri, 45(5), p.269 - 278, 2010/06
We report a new combined numerical approach for studying diluted magnetic semiconductors (DMS). In this approach, realistic parameters obtained by the 
calculation are used for performing quantum Monte Carlo calculations. We show that the proposed approach well describes the magnetic properties of DMS and can be used for designing the new DMS materials which has high Curie temperatures.
Yamamoto, Junichiro*; Futakawa, Masatoshi; Kurata, Yuji; Naoe, Takashi*
Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai (2002) Koen Rombunshu, p.1 - 2, 2002/09
no abstracts in English
Adachi, Hiroto; Oe, Junichiro; Takahashi, Saburo; Maekawa, Sadamichi
no journal, ,
It has been a conventional wisdom that a spin current is carried by conduction electrons in metals. However, it was recently demonstrated that there exist another type of spin current carried by low-lying excitations of localized spins, i.e., the spin-wave excitations. One of the important feature of the latter spin current, which we call here a spin-wave spin current, is that it can propagate over a distance as long as several millimeters. Moreover, a recent report on the spin Seebeck effect in an insulating magnet provide us with a good opportunity to discuss the scenario of spin-wave-mediated spin Seebeck effect. In this talk, we focus on the spin Seebeck effect observed in an insulating magnet of yttrium iron garnet, and discuss the scenario of spin-wave-mediated spin Seebeck effect.
Oe, Junichiro; Adachi, Hiroto; Takahashi, Saburo; Maekawa, Sadamichi
no journal, ,
In this report, we show the numerical study on the spin Seebeck effect by considering the magnetization dynamics in the presence of thermal gradient. The dynamics of the magnetization is given by solving the Landau-Lifshitz-Gilbert equation. We introduce the random magnetic field originated from finite temperatures which depends on the position. We calculate the spin current driven by the magnon in ferromagnetic sample. We also discuss the spin pumping to the normal probe attached to the sample for detecting the spin current.
Adachi, Hiroto; Takahashi, Saburo; Maekawa, Sadamichi; Oe, Junichiro
no journal, ,
We report the theoretical study on the thermal spin transport in ferromagnetic insulators. By using the fluctuation-dissipation theorem, we derive a random torque acting on the magnetic moment at the finite temperature. The numerical results shows the propagating spin wave that is driven by the thermal gradient. Furthermore, we argue a measurable voltage induced by the inverse spin Hall effect by using realistic parameters of actual setup.
Yamane, Yuta; Ieda, Junichi; Oe, Junichiro; Maekawa, Sadamichi
no journal, ,
no abstracts in English
Oe, Junichiro; Adachi, Hiroto; Takahashi, Saburo; Maekawa, Sadamichi
no journal, ,
Recently, the relation between the heat current and the spin current has much attracted from the view of the spintronics applications. The heat current induces the spin current, the spin Seebeck effect, has been discovered not only inferromagnetic metals but also in ferromagnetic semiconductors and ferromagnetic insulators. In this reports, we investigate the spin Seebeck effect by using the numerical simulation. We focus on the dynamics of the magnetization in the presence of the fluctuating torque which represents finite temperatures. The spin current is driven by the magnetization dynamics and converted to the charge current in a normal metal probe. We use the Landau-Lifshitz-Gilbert equation for calculating the magnetization dynamics and the diffusion equation for the dynamics of the conduction electrons. Our results show good agreement with the experimental results qualitatively.
