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568 results on '"Akiyama R"'

1. Superconducting proximity effect in a Rashba-type surface state of Pb/Ge(111)

Author

Huang, H., Toyama, H., Bondarenko, L. V., Tupchaya, A. Y., Gruznev, D. V., Takayama, A., Hobara, R., Akiyama, R., Zotov, A. V., Saranin, A. A., and Hasegawa, S.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The Rashba superconductor, in which spin-splitting bands become superconducting, is fascinating as a novel superconducting system in low dimensional systems. Here, we present the results of $\textit{in-situ}$ transport measurements on a Rashba-type surface state of the striped incommensurate (SIC) phase of a Pb atomic layer on Ge(111) surface with additional Pb islands/clusters on it. We found that two-step superconducting transitions at around 7 K and 3 K occurred. The latter superconducting transition is suggested to be induced at the non-superconducting Rashba SIC area because of the lateral proximity effect caused by the superconducting Pb clusters. Our results propose a new type of Rashba superconductor, which is a new platform to understand the Rashba superconducting systems.

Published
2019
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2. Two-dimensional conducting layer on SrTiO$_{3}$ surface induced by hydrogenation

Author

Takeuchi, Y., Hobara, R., Akiyama, R., Takayama, A., Ichinokura, S., Yukawa, R., Matsuda, I., and Hasegawa, S.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

We found that a surface state induced by hydrogenation on the surface of SrTiO$_{3}$(001) (STO) did not obey the rigid band model, which was confirmed by in situ electrical resistivity measurements in ultrahigh vacuum. With exposure of atomic hydrogen on the STO, a new surface state (H-induced donor state, HDS) appears within the bulk band gap (an in-gap state), which donates electrons thermally activated to the bulk conduction band, resulting in downward bending of the bulk bands beneath the surface. The doped electrons flow through the space-charge layer in two-dimensional manner parallel to the surface. The observed semiconducting behavior in the temperature dependence of electronic transport is explained by the thermal activation of carriers. The HDS and the bulk conduction band are non-rigid in energy position; they come closer with increasing the hydrogen adsorption. Eventually the HDS saturates its position around 88 meV below the bottom of the bulk conduction band. The sheet conductivity, accordingly, also saturates at 1.95$\pm$ 0.02 $\mu$ S/sq. with increasing hydrogen adsorption, corresponding to completion of the hydrogenation of the surface.

Published
2019
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3. Efficient Edelstein effects in one-atom-layer Tl-Pb compound

Author

Shiomi, Y., Yamamoto, K. T., Nakanishi, R., Nakamura, T., Ichinokura, S., Akiyama, R., Hasegawa, S., and Saitoh, E.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

We have investigated direct and inverse Edelstein effects in a one-atom-layer Tl-Pb compound with a large Rashba-type spin splitting. In spin pumping experiments at room temperature, spin-to-charge conversion voltage due to the inverse Edelstein effect is clearly observed in Py/Cu/Tl-Pb trilayer samples. To confirm efficient spin-charge interconversion in Tl-Pb compounds, the direct Edelstein effect is also studied in the same trilayer samples by measuring modulation of the effective magnetization damping in the Py layer via the charge-to-spin conversion in the Tl-Pb layer. Using both the results of direct and inverse Edelstein effects, the Edelstein length is estimated to be ~0.1 nm for Tl-Pb compounds., Comment: Appl. Phys. Lett

Published
2018
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4. Dynamic topological domain walls driven by lithium intercalation in graphene

Author

Endo, Y, Yan, X, Li, M, Akiyama, R, Brandl, C, Liu, JZ, Hobara, R, Hasegawa, S, Wan, W, Novoselov, KS, Tang, W-X, Endo, Y, Yan, X, Li, M, Akiyama, R, Brandl, C, Liu, JZ, Hobara, R, Hasegawa, S, Wan, W, Novoselov, KS, and Tang, W-X

Abstract

Stacking engineering in van der Waals (vdW) materials is a powerful method to control topological electronic phases for quantum device applications. Atomic intercalation into the vdW material can modulate the stacking structure at the atomic scale without a highly technical protocol. Here we report that lithium intercalation in a topologically structured graphene/buffer system on SiC(0001) drives dynamic topological domain wall (TDW) motions associated with stacking order change by using an in situ aberration-corrected low-energy electron microscope in combination with theoretical modelling. We observe sequential and selective lithium intercalation that starts at topological crossing points (AA stacking) and then selectively extends to AB stacking domains. Lithium intercalation locally changes the domain stacking order to AA and in turn alters the neighbouring TDW stacking orders, and continuous intercalation drives the evolution of the whole topological structure network. Our work reveals moving TDWs protected by the topology of stacking and lays the foundation for controlling the stacking structure via atomic intercalation. These findings open up new avenues to realize intercalation-driven vdW electronic devices.

Published
2023

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Author

AKIYAMA, R. and AKIYAMA, R.

Abstract

In the instrumentation of Der Ring des Nibelungen, Richard Wagner disposed specific instrumental parts that were perceived as strange in the contemporary practice of orchestras and military bands. These new parts play not supplemental, but central roles in the sound texture in the tetralogy. Basstrompete is the very case of Wagner's instrumentation technique. While the bass trumpet was the technical invention and development of the low brass section of nineteenth-century bands, musicological and organological research on this valve labrosone has focused on its use in Wagner's compositions. However, investigation on the history of the concept indicates hat the terminology and typology in the period of his composition was rather confounding. The critical concern during the technological upheaval in the manufacture and performance of the modern European labrosone was (re)defining the typological construction, sound conception, and cultural meaning of brass wind instruments. Wagner perceived this problem in the compositional process and experimented with an unknown instrumental timbre that could not be a part of other instrument sections. Basstrompete was not the solution for the amplification and standardization of the consort brass parts. Besides the terminological coincidence, Wagner's Basstrompete was an indeterminable instrument with its heterogenous sound alien to contemporary perception.

Published
2023

10. Electrical Observation of Soft-magnetic Skyrmions in the Sandwich Structure Including Topological Insulator with Self-assembled Ferromagnetic Atomic Layers

Author

TAKASHIRO, T., primary, AKIYAMA, R., additional, KIBIREV, I. A., additional, MATETSKIY, A. V., additional, NAKANISHI, R., additional, SATO, S., additional, FUKASAWA, T., additional, SASAKI, T., additional, TOYAMA, H., additional, HIWATARI, K. L., additional, ZOTOV, A. V., additional, SARANIN, A. A., additional, HIRAHARA, T., additional, and HASEGAWA, S., additional

Published
2022
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15. Predictors of Cerebral Aneurysm Rupture after Coil Embolization: Single-Center Experience with Recanalized Aneurysms

Author

Funakoshi, Y., primary, Imamura, H., additional, Tani, S., additional, Adachi, H., additional, Fukumitsu, R., additional, Sunohara, T., additional, Omura, Y., additional, Matsui, Y., additional, Sasaki, N., additional, Fukuda, T., additional, Akiyama, R., additional, Horiuchi, K., additional, Kajiura, S., additional, Shigeyasu, M., additional, Iihara, K., additional, and Sakai, N., additional

Published
2020
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22. Deuterium substitution effect on the excited-state dynamics of rhodopsin

Author

Kakitani, T., Akiyama, R., Hatano, Y., Imamoto, Y., Shichida, Y., Verdegem, P., and Lugtenburg, J.

Subjects
Substitution reactions -- Research, Deuterium -- Research, Rhodopsin -- Research, Excited state chemistry -- Research, Hydrogen bonding -- Research, Chemicals, plastics and rubber industries
Abstract

Research was conducted to examine the excited-state dynamics of the cis-trans photoisomerization of rhodopsin by investigating the deuterium substitution effects for hydrogen atoms bonded to C11 and C12 of the retinal chromophore by the method of Fourier transform of optical absorption spectra. Results indicate that the concerted motions of hydrogen out-of-plane waggings at C11 and C12, which are found to exist in native rhodopsin in the time range 20-60- fs, have no effect on the excited dynamics in its time range.

Published
1998

35. H-Mode Study in CHS

Author

Toi, K., Morisaki, T., Sakakibara, S., Ohdachi, S., Minami, T., Morita, S., Yamada, H., Tanaka, K., Katsumi Ida, Okamura, S., Ejiri, A., Iguchi, H., Nishimura, K., Matsuoka, K., Ando, A., Xu, J., Yamada, I., Narihara, K., Akiyama, R., Idei, H., Kubo, S., Ozaki, T., Takahashi, C., and Tsumori, K.

Subjects
Tokamak, Materials science, Hydrogen, General Engineering, Magnetic confinement fusion, chemistry.chemical_element, Plasma, law.invention, symbols.namesake, Deuterium, chemistry, law, Kinetic isotope effect, symbols, Electron temperature, Langmuir probe, Atomic physics
Abstract

In CHS rapid H-mode transition is observed in NBI heated deuterium and hydrogen plasmas without obvious isotope effect, when a net plasma current is ramped up to increase the external rotational transform. The H-mode of CHS has many similarities with those in tokamaks. Recent measurement with fast response Langmuir probes has revealed that the rapid change in floating potential occurs at the transition, but the change follows the formation of edge transport barrier. The presence of E = 1 surface near the edge and sawtooth crash triggered by internal modes may play an important role for determining the H-mode transition in CHS. 7 refs., 4 figs.

Published
1995
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44. HBx protein is indispensable for development of viraemia in human hepatocyte chimeric mice

Author

Tsuge, M., primary, Hiraga, N., additional, Akiyama, R., additional, Tanaka, S., additional, Matsushita, M., additional, Mitsui, F., additional, Abe, H., additional, Kitamura, S., additional, Hatakeyama, T., additional, Kimura, T., additional, Miki, D., additional, Mori, N., additional, Imamura, M., additional, Takahashi, S., additional, Hayes, C. N., additional, and Chayama, K., additional

Published
2010
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47. Overview of LHD Experiments

Author

Fujiwara, M., Kawahata, K., Ohyabu, N., Kaneko, O., Komori, A., Yamada, H., Ashikawa, N., Baylor, L. R., Combs, S. K., deVries, P. C., Emoto, M., Masuzaki, S., Minami, T., Miyajima, J., Morisaki, T., Morita, S., Murakami, S., Muto, S., Nagayama, Y., Nakajima, N., Nakamura, Y., Sagara, A., Nakanishi, H., Narihara, K., Nishimura, K., Noda, N., Notake, T., Ohdachi, S., Oka, Y., Okajima, S., Okamoto, M., Osakabe, M., Saito, K., Ozaki, T., Pavlichenko, R. O., Peterson, B. J., Sakakibara, S., Sakamoto, R., Sanuki, H., Sasao, H., Sasao, M., Sato, K., Sato, M., Seki, T., Watanabe, T., Shimozuma, T., Shoji, M., Sugama, H., Suzuki, H., Takechi, M., Takeiri, Y., Tamura, N., Tanaka, K., Toi, K., Tokuzawa, T., Wateri, T., Torii, Y., Tsumori, K., Watanabe, K. Y., Yamada, I., Yamaguchi, S., Yamamoto, S., Yokoyama, M., Yoshida, N., Yoshimura, Y., Zhao, Y. P., Akiyama, R., Kitagawa, S., Haba, K., Iima, M., Kodaira, J., Takita, T., Tsuzuki, T., Yamauchi, K., Yonezu, H., Chikaraishi, H., Hamaguchi, S., Imagawa, S., Kubota, Y., Inoue, N., Iwamoto, A., Mutoh, T., Maekawa, R., Mito, T., Murai, K., Nishimura, A., Takahata, K., Tamura, H., Yamada, S., Ejiri, A., Yanagi, N., Itoh, K., Matsuoka, K., Ohkubo, K., Ohtake, I., Satoh, S., Satow, T., Sudo, S., Tanahashi, S., Yamazaki, K., Fisher, P. W., Hamada, Y., Motojima, O., Funaba, H., Goto, M., Hartmann, D., Ida, K., Idei, H., Iio, S., Ikeda, K., Inagaki, S., Isobe, M., Kado, S., Khlopenkov, K., Kobuchi, T., Krasilnikov, A. V., Kubo, S., Kumazawa, R., Leuterer, F., Liang, Y., Lyon, J. F., Fujiwara, M., Kawahata, K., Ohyabu, N., Kaneko, O., Komori, A., Yamada, H., Ashikawa, N., Baylor, L. R., Combs, S. K., deVries, P. C., Emoto, M., Masuzaki, S., Minami, T., Miyajima, J., Morisaki, T., Morita, S., Murakami, S., Muto, S., Nagayama, Y., Nakajima, N., Nakamura, Y., Sagara, A., Nakanishi, H., Narihara, K., Nishimura, K., Noda, N., Notake, T., Ohdachi, S., Oka, Y., Okajima, S., Okamoto, M., Osakabe, M., Saito, K., Ozaki, T., Pavlichenko, R. O., Peterson, B. J., Sakakibara, S., Sakamoto, R., Sanuki, H., Sasao, H., Sasao, M., Sato, K., Sato, M., Seki, T., Watanabe, T., Shimozuma, T., Shoji, M., Sugama, H., Suzuki, H., Takechi, M., Takeiri, Y., Tamura, N., Tanaka, K., Toi, K., Tokuzawa, T., Wateri, T., Torii, Y., Tsumori, K., Watanabe, K. Y., Yamada, I., Yamaguchi, S., Yamamoto, S., Yokoyama, M., Yoshida, N., Yoshimura, Y., Zhao, Y. P., Akiyama, R., Kitagawa, S., Haba, K., Iima, M., Kodaira, J., Takita, T., Tsuzuki, T., Yamauchi, K., Yonezu, H., Chikaraishi, H., Hamaguchi, S., Imagawa, S., Kubota, Y., Inoue, N., Iwamoto, A., Mutoh, T., Maekawa, R., Mito, T., Murai, K., Nishimura, A., Takahata, K., Tamura, H., Yamada, S., Ejiri, A., Yanagi, N., Itoh, K., Matsuoka, K., Ohkubo, K., Ohtake, I., Satoh, S., Satow, T., Sudo, S., Tanahashi, S., Yamazaki, K., Fisher, P. W., Hamada, Y., Motojima, O., Funaba, H., Goto, M., Hartmann, D., Ida, K., Idei, H., Iio, S., Ikeda, K., Inagaki, S., Isobe, M., Kado, S., Khlopenkov, K., Kobuchi, T., Krasilnikov, A. V., Kubo, S., Kumazawa, R., Leuterer, F., Liang, Y., and Lyon, J. F.

Abstract

Experimental studies on the Large Helical Device during the last two years are reviewed. After the start of LHD experiment in 1998, the magnetic field has been gradually raised up to 2.89 T. The heating power has been increased, up to 4.2 MW for NBI, 1.3 MW for ICRF, and 0.9 MW for ECRH, Upgrading the key hardware systems has led to the extension of the plasma parameters to (i) higher T_e [ T_e(0) = 4.4 keV at = 5.3 x 10^18 m^-3 and P_abs = 1.8 MW ], (ii) higher confinement [tau_E = 0.3 s, T_e(0) = 1.1 keV at = 6.5 x 10^19 m^-3 and P_abs = 2.0 MW] and (iii) higher stored energy W_p^dia = 880 kJ. High performance plasmas have been realized in the inward shifted magnetic axis configuration (R=3 .6m) where the helical symmetry is recovered and the particle orbit properties are improved by trade off of MHD stability properties due to the appearance of the magnetic hill. The energy confinement was systematically higher than that predicted by the Intemational Stellerator Scaling 95 up to a factor of I .6 and was comparable with ELMy H-mode confinement capability in tokamaks. This confinement improvement is attributed to the configuration control (the inward shift of magnetic axis) and to the formation of the high edge temperature. The achieved average beta value reached 2.4 % at B=1.3 T, the highest beta value ever obtained in helical devices, and so far no degradation of confinement by MHD phenomenon is observed. The inward shifted configuration has also led to successful ICRF minority ion heating. ICRF power up to 1.3 MW was reliably injected into the plasma without significant impurity contamination and a plasma with a stored energy of 200 kJ was sustained for 5 sec by ICRF alone. As another important result long pulse discharges of more than I minute were successfully achieved separately with NBI heating of 0.5 MW and with ICRF heating of 0.85 MW.

Published
2000

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