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Yamanouchi, Michihiko*; Araki, Yasufumi; Sakai, Takaki*; Uemura, Tetsuya*; Ota, Hiromichi*; Ieda, Junichi
Science Advances (Internet), 8(15), p.eabl6192_1 - eabl6192_6, 2022/04
Times Cited Count：5 Percentile：80.8(Multidisciplinary Sciences)In a ferromagnetic Weyl metal SrRuO, a large effective magnetic field 
exerted on a magnetic domain wall (DW) by current has been reported. We show that the ratio of to current density exhibits nonmonotonic temperature dependence and surpasses those of conventional spin-transfer torques and spin-orbit torques. This enhancement is described well by topological Hall torque (THT), which is exerted on a DW by Weyl electrons emerging around Weyl points when an electric field is applied across the DW. The ratio of the arising from the THT to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques reported in metallic systems, showing that the THT may provide a better way for energy-efficient manipulation of magnetization in spintronics devices.
He neutron spin filter at J-PARCOkudaira, Takuya; Oku, Takayuki; Ino, Takashi*; Hayashida, Hirotoshi*; Kira, Hiroshi*; Sakai, Kenji; Hiroi, Kosuke; Takahashi, Shingo*; Aizawa, Kazuya; Endo, Hitoshi*; et al.
Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10
Times Cited Count：9 Percentile：82.12(Instruments & Instrumentation)Oku, Takayuki; Nakamura, Mitsutaka; Sakai, Kenji; Teshigawara, Makoto; Tatsumoto, Hideki*; Yonemura, Masao*; Suzuki, Junichi*; Arai, Masatoshi*
JAEA-Conf 2015-002, 660 Pages, 2016/02
JAEA-Conf-2015-002.pdf:168.34MB
The twenty first meeting of the International Collaboration on Advanced Neutron Source (ICANS-XXI) was held at Ibaraki Prefectural Culture Center in Mito from 29 September to 3 October 2014. It was hosted by Japan Atomic Energy Agency (JAEA), High Energy Accelerator Research Organization (KEK) and Comprehensive Research Organization for Science and Society (CROSS). In the meeting, new science and technology in the new era with the high power neuron sources were discussed in mostly "workshop style" sessions. In each session, various kinds of issues related to not only the hardware, but also the software and even radiation safety were discussed with the keyword of "INTERFACE". More than 200 Papers were presented in the meeting and 72 contributed papers are compiled in the proceedings.
He Neutron Spin Filter (NSF) in the MLF at J-PARCSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.
JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09
The polarized He filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring He nuclear spin polarization 
of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the monitor.
Aoki, So; Taniguchi, Tomomi*; Sakai, Junichi*
Zairyo To Kankyo, 64(9), p.414 - 420, 2015/09
The objective of this study is to clarify the preferential dissolution mechanism of a duplex stainless steel (DSS) at its corrosion potential by means of in-situ Scanning Electrochemical Microscope observation. Probe electrode was fixed above ferritic and austenitic each phase of DSS at corrosion potential. Potential of the probe electrode was polarized toward noble direction, and probe current was measured. In a probe potential range of 0-0.70 V (SHE), anodic current due to hydrogen oxidation reaction could be detected. This anodic current was larger above austenitic phase than that above ferritic phase. In a probe potential range of 0.70-1.2 V, anodic current due to Fe
oxidation reaction to Fe
could be detected. This anodic current was larger above ferritic phase than that above austenitic phase. Based on these results, a preferential dissolution mechanism model of a DSS at the corrosion potential is proposed using internal polarization curves.
Aoki, So; Nada, Yushi*; Sakai, Junichi*
Zairyo To Kankyo, 64(8), p.366 - 372, 2015/08
The objective of this study is to clarify dissolution behavior of duplex stainless steels in crevice corrosion growth step. Crevice corrosion grew on the duplex stainless steels by holding potential at various values. After a certain period, dissolution behavior of the crevice corrosion was analyzed based on observation of corroded area. Change in crevice corrosion dissolution behavior with time was also investigated by means of in-situ observation. Four types of dissolution regions could be observed in the corrosion area from outside toward inside direction, i.e. tip of the corroded area toward initiation point, in a crevice; they were passive region, the preferential dissolution region of austenitic phase, both phase dissolution region, and the preferential dissolution region of ferritic phase. The crevice corrosion which maintained that four dissolution regions grew toward the edge of the crevice. This dissolution behavior was given at all the potential where crevice corrosion occurred. The result is described by the micro galvanic cell between inside and outside the crevice consists of IR drop.
Haku, Satoshi*; Tashiro, Takaharu*; Nakayama, Hiroyasu*; Ieda, Junichi; Entani, Shiro; Sakai, Seiji; Ando, Kazuya*
Applied Physics Express, 8(7), p.073009_1 - 073009_3, 2015/07
Times Cited Count：5 Percentile：23.46(Physics, Applied)We found that the spin pumping in a Ni
Fe
/Pt bilayer is strongly suppressed by inserting single-layer graphene (SLG) at the interface. The spin pumping in the NiFe/Pt bilayer enhances the magnetization damping of the ferromagnetic layer, which is quantified from microwave frequency dependence of ferromagnetic resonance linewidth. We show that the enhancement of the magnetization damping due to the spin pumping disappears in a NiFe/SLG/Pt trilayer. This result indicates that the spin pumping is blocked by the atomic monolayer, demonstrating the crucial role of the interfacial short-range spin-exchange coupling in the spin pumping in metallic systems.
Fuji, Hiroyuki*; Aoki, So; Ishii, Tomohiro*; Sakai, Junichi*
Zairyo To Kankyo, 64(5), p.178 - 182, 2015/05
This study focused on a breakdown of passive film which is followed by rust staining, and the objective of this study was to clarify the effect of stability of passive film on the resistance of rust staining of stainless steels. Atomospheric exposure test was carried out for 12 months. In order to compare the stability of passive film, measurements of potential-decay curves, and potentiostatic polarization tests were performed in acidic aqueous chloride solution. As a result, rust area of austenitic stainless steel was higher than that of ferritic stainless steel. This order didn't follow the orders of pitting potentials and densities of inclusions on surface between specimens. On the contrary, the order of the resistance of rust staining of stainless steels followed the order of the stability of passive film. One of the reasons why the resistance of rust staining of austenitic stainless steel was worse than that of ferritic stainless steel was seemed that chloride more easily broke passive film on the surface of austenitic stainless and formed micro pits which become initiations of rust staining and increase density of stains.
He neutron spin filter and its application to magnetic field imaging at J-PARCSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi; Kira, Hiroshi*; Shinohara, Takenao; Oikawa, Kenichi; Harada, Masahide; Kakurai, Kazuhisa; Aizawa, Kazuya; Arai, Masatoshi; et al.
Journal of Physics; Conference Series, 528, p.012016_1 - 012016_7, 2014/07
Times Cited Count：2 Percentile：69.7In polarized neutron experiments, it is interested in expanding measurable neutron energy region up to epithermal neutrons. For realizing this situation, a Polarized He Spin Flipper (PHSF) has a key role because it can polarize from cold to epithermal neutrons, and flip neutron spins by flipping the He nuclear spin direction. We have developed the portable PHSF consisting of a cylindrical glass cell filled with He gas which is installed a solenoid coil of 20 cm in diameter and 30 cm long. After polarizing the He gas by irradiating a laser light based on a SEOP technique, the PHSF is brought by hands to experimental areas with kept its polarization. We carried out the feasibility test on our portable PHSF in the MLF of J-PARC and demonstrated it worked well by evaluating flipping ratios of polarized neutrons and attempting to visualize magnetic fields generated by sample coils.
Sakai, Kenji; Oku, Takayuki; Shinohara, Takenao; Kira, Hiroshi; Oi, Motoki; Maekawa, Fujio; Kakurai, Kazuhisa; Ino, Takashi*; Arimoto, Yasushi*; Shimizu, Hirohiko*; et al.
Journal of Physics; Conference Series, 340, p.012037_1 - 012037_7, 2012/02
Times Cited Count：2 Percentile：62.89At the Materials and Life science experimental Facility (MLF) in J-PARC, an experiment of detecting a neutron polarizing ability caused by a neutron-nuclear (n-N) spin correlation term at a resonant peak of 
Xe is planned. The Xe gas having a high polarization under low magnetic field and room temperature by a spin exchange optical pumping (SEOP) technique is expected to become a suitable target for verification of the neutron optical theorem (NOPT). We evaluated measurable quantities based on the NOPT, developed a polarized Xe gas system, and carried out a feasibility test of our apparatus. This paper reports on the present status of the experiment.
Yokoyama, Kenichi*; Murata, Yusuke*; Shiimori, Fusae*; Sakai, Junichi*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.11 - 12, 2011/09
Characteristics of hydrogen embrittlement of pure Ti and Ti-5Ta alloys were evaluated by stress loading and constant load tests. Mechanical properties of these materials were affected by hydride formation of surface layers. Although elongation was reduced by hydrogen absorption, embrittlement was observed only in the surface hydride area. It is also suggested that Ti-5Ta alloy was better susceptibility of hydrogen embrittlement than pure Ti.
Shiimori, Fusae*; Sakai, Junichi*; Yokoyama, Kenichi*; Motooka, Takafumi; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*
Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.13 - 14, 2011/09
In reprocessing plants, hydrogen gas was released by radiolysis of aqueous solution. The relationship of the amount of hydrogen gas and the amount of hydrogen absorption to titanium and Ti-5Ta were not clear. In this study, hydrogen was absorbed to titanium by the cathode charging and irradiation. Then, the amount of the hydrogen gas from solutions and the amount of the hydrogen absorbed to titanium was compared. It was found that a very small amount of the hydrogen by radiolysis was absorbed to titanium. It was suggested that the difference of the hydrogen absorption rate was caused by the difference of the hydrogen concentration on the metal surface.
Shinohara, Takenao; Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Harada, Masahide; Oikawa, Kenichi; Maekawa, Fujio; Suzuki, Junichi; Oku, Takayuki; Takata, Shinichi; et al.
Nuclear Instruments and Methods in Physics Research A, 651(1), p.121 - 125, 2011/09
Times Cited Count：26 Percentile：87.6(Instruments & Instrumentation)no abstracts in English
He neutron spin filters on the small-angle neutron scattering spectrometer SANS-J-IISakaguchi, Yoshifumi; Kira, Hiroshi; Oku, Takayuki; Shinohara, Takenao; Suzuki, Junichi; Sakai, Kenji; Nakamura, Mitsutaka; Aizawa, Kazuya; Arai, Masatoshi; Noda, Yohei; et al.
Journal of Physics; Conference Series, 294(1), p.012017_1 - 012017_7, 2011/06
Times Cited Count：2 Percentile：65.78He neutron spin filter cellsSakaguchi, Yoshifumi; Kira, Hiroshi; Oku, Takayuki; Shinohara, Takenao; Suzuki, Junichi; Sakai, Kenji; Nakamura, Mitsutaka; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; et al.
Journal of Physics; Conference Series, 294(1), p.012004_1 - 012004_7, 2011/06
Times Cited Count：2 Percentile：65.78He neutron spin filtersSakaguchi, Yoshifumi; Kira, Hiroshi; Oku, Takayuki; Shinohara, Takenao; Suzuki, Junichi; Sakai, Kenji; Nakamura, Mitsutaka; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; et al.
Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06
He neutron spin filtersSakaguchi, Yoshifumi; Kira, Hiroshi; Oku, Takayuki; Shinohara, Takenao; Suzuki, Junichi; Sakai, Kenji; Nakamura, Mitsutaka; Suzuya, Kentaro; Aizawa, Kazuya; Arai, Masatoshi; et al.
Physica B; Condensed Matter, 406(12), p.2443 - 2447, 2011/06
Times Cited Count：3 Percentile：16.46(Physics, Condensed Matter)He neutron spin filter cellsSakaguchi, Yoshifumi; Kira, Hiroshi; Oku, Takayuki; Shinohara, Takenao; Suzuki, Junichi; Sakai, Kenji; Nakamura, Mitsutaka; Suzuya, Kentaro; Arai, Masatoshi; Takeda, Masayasu; et al.
Nuclear Instruments and Methods in Physics Research A, 634(1, Suppl.), p.S122 - S125, 2011/04
Mishima, Kenji*; Ino, Takashi*; Sakai, Kenji; Shinohara, Takenao; Hirota, Katsuya*; Ikeda, Kazuaki*; Sato, Hiromi*; Otake, Yoshie*; Omori, Hitoshi*; Muto, Suguru*; et al.
Nuclear Instruments and Methods in Physics Research A, 600, p.342 - 345, 2009/02
Times Cited Count：27 Percentile：85.36(Instruments & Instrumentation)A new beamline for a fundamental physics experiment is under construction at BL05 port in the Materials and Life Science Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC), this beamline is designed using novel techniques of neutron optics and it is termed "Neutron Optics and Physics". The beam from the moderator is deflected by multi-channel supermirrors and split into three branches for individual experiments. In this study, we have optimized the design of the beam optics and shields using the Monte Carlo simulation package PHITS. The neutron fluxes of beams are expected to be 
cm
str
sMW, 
cm
sMW, 
cmsMW, with polarization of 99.8%.
Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.
Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01
Times Cited Count：51 Percentile：71.65(Biochemistry & Molecular Biology)Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.
