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Journal Articles

Enhanced $$d$$-$$p$$ hybridization intertwined with anomalous ground state formation in the van der Waals itinerant magnet Fe$$_5$$GeTe$$_2$$

Yamagami, Kohei*; Fujisawa, Yuita*; Markel, P.-A.*; Barnaby, S.*; Sumida, Kazuki; Takeda, Yukiharu; Okada, Yoshinori*

Physical Review B, 106(4), p.045137_1 - 045137_8, 2022/07

Journal Articles

Short-range magnetic interaction in a monolayer 1$$T$$-VSe$$_2$$ film revealed by element-specific X-ray magnetic circular dichroism

Sumida, Kazuki; Takeda, Yukiharu; Kusaka, Shotaro*; Kobayashi, Katsuyoshi*; Hirahara, Toru*

Physical Review Materials (Internet), 6(1), p.014006_1 - 014006_8, 2022/01

 Times Cited Count:1 Percentile:0(Materials Science, Multidisciplinary)

We investigated the intrinsic magnetic properties of the two-dimensional ferromagnetic candidate monolayer 1$$T$$-VSe$$_2$$ films using X-ray magnetic circular dichroism (XMCD), an element-specific magnetic probe. By performing high-resolution measurements, we succeeded in detecting a clear XMCD signal from the atomically thin 1$$T$$-VSe$$_2$$ films under an external magnetic field. Through manipulation of the X-ray incidence angle, we were able to disentangle the in-plane and out-of-plane magnetic properties and found a strong magnetic anisotropy. Moreover, magnetic field- and temperature-dependent XMCD revealed that there is no long-range ferromagnetic ordering even at 6 K, but short-range ferromagnetic and antiferromagnetic interactions between neighboring vanadium ions exist. Such low-temperature magnetic behavior signifies that the monolayer 1$$T$$-VSe$$_2$$ is on the verge of ferromagnetism, and this fact accounts for the reported ferromagnetism in VSe$$_2$$-based heterostructures.

Journal Articles

Absence of ferromagnetism in MnBi$$_2$$Te$$_4$$/Bi$$_2$$Te$$_3$$ down to 6 K

Fukasawa, Takuro*; Kusaka, Shotaro*; Sumida, Kazuki; Hashizume, Mizuki*; Ichinokura, Satoru*; Takeda, Yukiharu; Ideta, Shinichiro*; Tanaka, Kiyohisa*; Shimizu, Ryota*; Hitosugi, Taro*; et al.

Physical Review B, 103(20), p.205405_1 - 205405_6, 2021/05

 Times Cited Count:3 Percentile:56.59(Materials Science, Multidisciplinary)

Journal Articles

Fabrication of a novel magnetic topological heterostructure and temperature evolution of its massive Dirac cone

Hirahara, Toru*; Otrokov, M. M.*; Sasaki, Taisuke*; Sumida, Kazuki*; Tomohiro, Yuta*; Kusaka, Shotaro*; Okuyama, Yuma*; Ichinokura, Satoru*; Kobayashi, Masaki*; Takeda, Yukiharu; et al.

Nature Communications (Internet), 11, p.4821_1 - 4821_8, 2020/09

 Times Cited Count:24 Percentile:92.77(Multidisciplinary Sciences)

Journal Articles

Unveiling spin-dependent unoccupied electronic states of Co$$_{2}$$MnGe (Ga) film via Ge (Ga) $$L_{2,3}$$ absorption spectroscopy

Yoshikawa, Tomoki*; Antonov, V. N.*; Kono, Takashi*; Kakoki, Masaaki*; Sumida, Kazuki; Miyamoto, Koji*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; Sakuraba, Yuya*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

 Times Cited Count:1 Percentile:12.46(Materials Science, Multidisciplinary)

Journal Articles

Key factors controlling radiocesium sorption and fixation in river sediments around the Fukushima Daiichi Nuclear Power Plant, 2; Sorption and fixation behaviors and their relationship to sediment properties

Tachi, Yukio; Sato, Tomofumi*; Takeda, Chizuko*; Ishidera, Takamitsu; Fujiwara, Kenso; Iijima, Kazuki

Science of the Total Environment, 724, p.138097_1 - 138097_10, 2020/07

 Times Cited Count:7 Percentile:59.98(Environmental Sciences)

To understand and predict radiocesium transport behaviors in the environment, sorption and fixation behaviors of radiocesium on river sediments from Ukedo and Odaka rivers around the Fukushima Daiichi Nuclear Power Plant were investigated systematically focusing on Cs sorption and fixation mechanisms and their relationship with Cs concentrations and sediment properties including clay mineralogy and organic matter.

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:11 Percentile:78.03(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Element-specific density of states of Co$$_{2}$$MnGe revealed by resonant photoelectron spectroscopy

Kono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki*; Miyamoto, Koji*; Muro, Takayuki*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; et al.

Physical Review B, 100(16), p.165120_1 - 165120_6, 2019/10

 Times Cited Count:4 Percentile:32.8(Materials Science, Multidisciplinary)

Journal Articles

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb$$_{2-x}$$V$$_{x}$$Te$$_{3}$$

Sumida, Kazuki*; Kakoki, Masaaki*; Reimann, J.*; Nurmamat, M.*; Goto, Shinichi*; Takeda, Yukiharu; Saito, Yuji; Kokh, K. A.*; Tereshchenko, O. E.*; G$"u$dde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

 Times Cited Count:7 Percentile:59.16(Physics, Multidisciplinary)

Journal Articles

Negative Te spin polarization responsible for ferromagnetic order in the doped topological insulator V$$_{0.04}$$(Sb$$_{1-x}$$Bi$$_{x}$$)$$_{1.96}$$Te$$_{3}$$

Ye, M.*; Xu, T.*; Li, G.*; Qiao, S.*; Takeda, Yukiharu; Saito, Yuji; Zhu, S.-Y.*; Nurmamat, M.*; Sumida, Kazuki*; Ishida, Yukiaki*; et al.

Physical Review B, 99(14), p.144413_1 - 144413_7, 2019/04

AA2018-0697.pdf:1.89MB

 Times Cited Count:10 Percentile:60.99(Materials Science, Multidisciplinary)

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Carrier-mediated ferromagnetism in the magnetic topological insulator Cr-doped (Sb,Bi)$$_{2}$$Te$$_{3}$$

Ye, M.*; Li, W.*; Zhu, S.-Y.*; Takeda, Yukiharu; Saito, Yuji; Wang, J.*; Pan, H.*; Nurmamat, M.*; Sumida, Kazuki*; Ji, F.*; et al.

Nature Communications (Internet), 6, p.8913_1 - 8913_7, 2015/11

AA2015-0647.pdf:0.64MB

 Times Cited Count:46 Percentile:90.21(Multidisciplinary Sciences)

Magnetically doped topological insulators are predicted to exhibit exotic phenomena including the quantized anomalous Hall effect and a dissipationless transport, which facilitate the development of low-power-consumption devices using electron spins. The realization of the quantized anomalous Hall effect is so far restricted to the Cr-doped (Sb,Bi)$$_{2}$$Te$$_{3}$$ system at extremely low temperature; however, the microscopic origin of its ferromagnetism is poorly understood. Here we present an element-resolved study for Cr-doped (Sb,Bi)$$_{2}$$Te$$_{3}$$ using X-ray magnetic circular dichroism to unambiguously show that the long-range magnetic order is mediated by the p-hole carriers of the host lattice, and the interaction between the Sb(Te) p and Cr d states is crucial.

Journal Articles

Spectroscopic evidence of band Jahn-Teller distortion upon martensitic phase transition in Heusler-type Ni-Fe(Co)-Ga ferromagnetic shape-memory alloy films

Sumida, Kazuki*; Shirai, Kaito*; Zhu, S.-Y.*; Taniguchi, Masaki*; Ye, M.*; Ueda, Shigenori*; Takeda, Yukiharu; Saito, Yuji; Aseguinolaza, I. R.*; Barandiar$'a$n, J. M.*; et al.

Physical Review B, 91(13), p.134417_1 - 134417_6, 2015/04

 Times Cited Count:5 Percentile:26.71(Materials Science, Multidisciplinary)

Journal Articles

Elucidations of the catalytic cycle of NADH-cytochrome $$b$$$$_{5}$$ reductase by X-ray crystallography; New insights into regulation of efficient electron transfer

Yamada, Mitsugu*; Tamada, Taro; Takeda, Kazuki*; Matsumoto, Fumiko*; Ono, Hiraku*; Kosugi, Masayuki*; Takaba, Kiyofumi*; Shoyama, Yoshinari*; Kimura, Shigenobu*; Kuroki, Ryota; et al.

Journal of Molecular Biology, 425(22), p.4295 - 4306, 2013/11

 Times Cited Count:18 Percentile:49.48(Biochemistry & Molecular Biology)

NADH-Cytochrome $$b$$$$_{5}$$ reductase (b5R), a flavoprotein consisting of NADH and flavin adenine dinucleotide (FAD) binding domains, catalyzes electron transfer from the two-electron carrier NADH to the one-electron carrier cytochrome $$b$$$$_{5}$$ (Cb5). The crystal structures of both the fully reduced form and the oxidized form of porcine liver b5R were determined. In the reduced b5R structure determined at 1.68${AA}$ resolution, the relative configuration of the two domains was slightly shifted in comparison with that of the oxidized form. This shift resulted in an increase in the solvent-accessible surface area of FAD and created a new hydrogen-bonding interaction between the N5 atom of the isoalloxazine ring of FAD and the hydroxyl oxygen atom of Thr66, which is considered to be a key residue in the release of a proton from the N5 atom. The isoalloxazine ring of FAD in the reduced form is flat as in the oxidized form and stacked together with the nicotinamide ring of NAD$$^{+}$$. Determination of the oxidized b5R structure, including the hydrogen atoms, determined at 0.78${AA}$ resolution revealed the details of a hydrogen-bonding network from the N5 atom of FAD to His49 via Thr66. Both of the reduced and oxidized b5R structures explain how backflow in this catalytic cycle is prevented and the transfer of electrons to one-electron acceptors such as Cb5 is accelerated. Furthermore, crystallographic analysis by the cryo-trapping method suggests that re-oxidation follows a two-step mechanism. These results provide structural insights into the catalytic cycle of b5R.

Journal Articles

Experimental evidence of nonthermal acceleration of relativistic electrons by an intensive laser pulse

Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.

Physical Review E, 83(2), p.026401_1 - 026401_6, 2011/02

 Times Cited Count:15 Percentile:66.63(Physics, Fluids & Plasmas)

An energy distribution function of energetic particles in the universe or cosmic rays is well represented by a power-law spectrum, therefore, nonthermal acceleration is essential to understand the origin of cosmic rays. A possible candidate for the origin of cosmic rays is wakefield acceleration at relativistic astrophysical perpendicular shocks. Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma.

Journal Articles

Model experiment of cosmic ray acceleration due to an incoherent wakefield induced by an intense laser pulse

Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.

Physics of Plasmas, 18(1), p.010701_1 - 010701_4, 2011/01

 Times Cited Count:18 Percentile:63.9(Physics, Fluids & Plasmas)

Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma. An intensive laser pulse was propagated in a plasma tube created by imploding a hollow polystyrene cylinder, as the large amplitude light waves propagated in the upstream plasma at an astrophysical shock. Nonthermal electrons were generated, and the energy distribution functions of the electrons have a power-law component with an index of 2.

Journal Articles

Spectrum modulation of relativistic electrons by laser wakefield

Nakanii, Nobuhiko*; Kondo, Kiminori; Kuramitsu, Yasuhiro*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; Tanimoto, Tsuyoshi*; et al.

Applied Physics Letters, 93(8), p.081501_1 - 081501_3, 2008/08

 Times Cited Count:4 Percentile:19.55(Physics, Applied)

Energetic electrons were generated by the interaction of a high-intensity laser pulse with a plasma preformed from a hollow plastic cylinder via laser-driven implosion. The spectra of a comparatively high-density plasma had a bump around 10 MeV. Simple numerical calculations explained the spectra obtained in this experiment. This indicates that the plasma tube has sufficient potential to convert a Maxwellian spectrum to a comparatively narrow spectrum.

Oral presentation

Crystallization of cytochrome b5 reductase aimed to neutron crystallography

Shoyama, Yoshinari; Tamada, Taro; Kuroki, Ryota; Kimura, Shigenobu*; Takeda, Kazuki*; Hayashi, Takuro*; Miki, Kunio*

no journal, , 

NADH-cytochrome b5 reductase (b5R) is a pyridine nucleotide-dependent flavin reductase which contains a FAD in a molecule. The b5R catalyzes the electron transfer from NADH to cytochrome b5. The b5R is related to fatty acid metabolism and reduction of cytochrome P450. In order to clarify detailed structure of b5R, we carried out purification of b5R from E coli cell according to the method previously reported. Since a large-size crystal is necessary for the neutron structure analysis, we addressed enlargement of crystal by macroseeding method and periodical addition of protein sample to the crystallization solution. We succeeded in a preparation of large-scale crystal with a size of 1.0$$times$$0.5$$times$$0.3 mm, which is suitable for preliminary neutron diffraction study.

Oral presentation

Crystallization of NADH-cytochrome ${it b}$$$_{5}$$ reductase aimed to neutron crystallography

Shoyama, Yoshinari; Tamada, Taro; Kuroki, Ryota; Kimura, Shigenobu*; Takeda, Kazuki*; Hayashi, Takuro*; Miki, Kunio*

no journal, , 

NADH-cytochrome ${it b}$ $$_{5}$$ reductase (b5R) is a pyridine nucleotide-dependent flavin reductase which contains a FAD in a molecule. The b5R catalyzes the electron transfer from NADH to cytochrome b5. The b5R is related to fatty acid metabolism and reduction of cytochrome P450. In order to clarify detailed structure of b5R, we carried out purification of b5R from E coli cell according to the method previously reported. Since a large-size crystal is necessary for the neutron structure analysis. We addressed enlargement of crystal by macroseeding method and periodical addition of protein sample to the crystallization solution. We succeeded in a preparation of large-scale crystal with volume of 4 mm$$^{3}$$, and we did preliminary neutron diffraction study using this crystal. Then we got 2${AA}$ resolution neutron diffraction data at BIX4.

Oral presentation

Structural analysis of reaction intermediates of cytochrome ${it b$_{5}$}$ reductase

Yamada, Mitsugu; Tamada, Taro; Matsumoto, Fumiko; Takeda, Kazuki*; Kimura, Shigenobu*; Kuroki, Ryota; Miki, Kunio*

no journal, , 

no abstracts in English

32 (Records 1-20 displayed on this page)