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2. Exciton-dielectric mode coupling in MoS2 nanoflakes visualized by cathodoluminescence

Author

Vu Dung Thi, Matthaiakakis Nikolaos, Saito Hikaru, and Sannomiya Takumi

Subjects
cathodoluminescence, exciton-dielectric mode coupling, localized field, molybdenum disulfide, scanning transmission electron microscopy, Physics, QC1-999
Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDCs), possessing unique exciton luminescence properties, have attracted significant attention for use in optical and electrical devices. TMDCs are also high refractive index materials that can strongly confine the electromagnetic field in nanoscale dimensions when patterned into nanostructures, thus resulting in complex light emission that includes exciton and dielectric resonances. Here, we use cathodoluminescence (CL) to experimentally visualize the emission modes of single molybdenum disulfide (MoS2) nanoflakes and to investigate luminescence enhancement due to dielectric resonances in nanoscale dimensions, by using a scanning transmission electron microscope. Specifically, we identify dielectric modes whose resonant wavelength is sensitive to the shape and size of the nanoflake, and exciton emission peaks whose energies are insensitive to the geometry of the flakes. Using a four-dimensional CL method and boundary element method simulations, we further theoretically and experimentally visualize the emission polarization and angular emission patterns, revealing the coupling of the exciton and dielectric resonant modes. Such nanoscopic observation provides a detailed understanding of the optical responses of MoS2 including modal couplings of excitons and dielectric resonances which play a crucial role in the development of energy conversion devices, single-photon emitters, and nanophotonic circuits with enhanced light-matter interactions.

Published
2022
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4. Time-correlated electron and photon counting microscopy

Author

Yanagimoto, Sotatsu, Yamamoto, Naoki, Yuge, Tatsuro, Saito, Hikaru, Akiba, Keiichirou, and Sannomiya, Takumi

Subjects
Physics - Instrumentation and Detectors, Physics - Optics
Abstract

Electron microscopy based on high-energy electrons allows nanoscopic analytical imaging taking advantage of secondarily generated particles. Especially for cathodoluminescence, the correlation between primary incident electrons and emitted photons includes information on the entire interaction process. However, electron-photon time correlation tracking the relaxation dynamics of luminescent materials has so far not been achieved. In this work, we propose time-correlated electron and photon counting microscopy, where coincidence events of primary electrons and generated photons are counted after interaction. The electron-photon time correlation enables extracting a unique lifetime of the emitter independent of the photon state, accounting for coherent and incoherent photon generation processes. We also introduce a correlation factor and discuss the correlation between electrons and generated coherent photons. Through momentum selection, we observe correlation changes indicating the presence of pair correlation originated from the electron-photon entanglement. The present work lays the foundation for developing next-generation electron microscopy based on quantum correlation.

Published
2023
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7. K-doped Ba122 epitaxial thin film on MgO substrate by buffer engineering

Author

Qin, Dongyi, Iida, Kazumasa, Guo, Zimeng, Wang, Chao, Saito, Hikaru, Hata, Satoshi, Naito, Michio, and Yamamoto, Akiyasu

Subjects
Condensed Matter - Superconductivity
Abstract

Molecular beam epitaxy of K-doped Ba122 (Ba$_{1-x}$K$_x$Fe$_\text{2}$As$_\text{2}$) superconductor was realized on a MgO substrate. Microstructural observation revealed that the undoped Ba122 served as a perfect buffer layer for epitaxial growth of the K-doped Ba122. The film exhibited a high critical temperature of 39.8 K and a high critical current density of 3.9 MA/cm$^\text{2}$ at 4 K. The successful growth of epitaxial thin film will enable artificial single grain boundary on oxide bicrystal substrates and reveal the grain boundary transport nature of K-doped Ba122., Comment: 5 pages, 4 figures, accepted manuscript Supercond. Sci. Technol 2022

Published
2022
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8. Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples

Author

Matsumoto, Toru, Noguchi, Takaaki, Miyake, Akira, Igami, Yohei, Haruta, Mitsutaka, Seto, Yusuke, Miyahara, Masaaki, Tomioka, Naotaka, Saito, Hikaru, Hata, Satoshi, Harries, Dennis, Takigawa, Aki, Nakauchi, Yusuke, Tachibana, Shogo, Nakamura, Tomoki, Matsumoto, Megumi, Ishii, Hope A., Bradley, John P., Ohtaki, Kenta, Dobrică, Elena, Leroux, Hugues, Le Guillou, Corentin, Jacob, Damien, de la Peña, Francisco, Laforet, Sylvain, Marinova, Maya, Langenhorst, Falko, Beck, Pierre, Phan, Thi H. V., Rebois, Rolando, Abreu, Neyda M., Gray, Jennifer, Zega, Thomas, Zanetta, Pierre-M., Thompson, Michelle S., Stroud, Rhonda, Burgess, Kate, Cymes, Brittany A., Bridges, John C., Hicks, Leon, Lee, Martin R., Daly, Luke, Bland, Phil A., Zolensky, Michael E., Frank, David R., Martinez, James, Tsuchiyama, Akira, Yasutake, Masahiro, Matsuno, Junya, Okumura, Shota, Mitsukawa, Itaru, Uesugi, Kentaro, Uesugi, Masayuki, Takeuchi, Akihisa, Sun, Mingqi, Enju, Satomi, Michikami, Tatsuhiro, Yurimoto, Hisayoshi, Okazaki, Ryuji, Yabuta, Hikaru, Naraoka, Hiroshi, Sakamoto, Kanako, Yada, Toru, Nishimura, Masahiro, Nakato, Aiko, Miyazaki, Akiko, Yogata, Kasumi, Abe, Masanao, Okada, Tatsuaki, Usui, Tomohiro, Yoshikawa, Makoto, Saiki, Takanao, Tanaka, Satoshi, Terui, Fuyuto, Nakazawa, Satoru, Watanabe, Sei-ichiro, and Tsuda, Yuichi

Published
2024
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10. Approaching the ultimate superconducting properties of (Ba,K)Fe2As2 by naturally formed low-angle grain boundary networks

Author

Iida, Kazumasa, Qin, Dongyi, Tarantini, Chiara, Hatano, Takafumi, Wang, Chao, Guo, Zimeng, Gao, Hongy, Saito, Hikaru, Hata, Satoshi, Naito, Michio, and Yamamoto, Akiyasu

Subjects
Condensed Matter - Superconductivity
Abstract

The most effective way to enhance the dissipation-free supercurrent in presence of magnetic field for type II superconductors is the introduction of defects that acts as artificial pinning centres (APCs) for the vortices. For instance, the in-field critical current density of doped BaFe2As2 (Ba122), one of the most technologically important Fe-based superconductors, has been improved over the last decade by APCs created by ion-irradiation. The technique of ion-irradiation has been commonly implemented to determine the ultimate superconducting properties. However, this method is rather complicated and expensive. Here, we report on a surprisingly high critical current density and strong pinning efficiency close to the crystallographic c-axis for a K-doped Ba122 epitaxial thin film without APCs, achieving performance comparable to ion-irradiated K-doped Ba122 single crystals. Microstructural analysis reveals that the film is composed of columnar grains having width around 30-60 nm. The grains are rotated around the b- (or a-) axis by 1.5 degree and around the c-axis by -1 degree, resulting in the formation of low-angle grain boundary networks. This study demonstrates that the upper limit of in-field properties reached in ion-irradiated K-doped Ba122 is achievable by grain boundary engineering, which is a simple and industrially scalable manner., Comment: Main text with Supplement Material

Published
2021
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11. High $J_{\rm c}$ and low anisotropy of hydrogen doped NdFeAsO superconducting thin film

Author

Iida, Kazumasa, Hänisch, Jens, Kondo, Keisuke, Chen, Mingyu, Hatano, Takafumi, Wang, Chao, Saito, Hikaru, Hata, Satoshi, and Ikuta, Hiroshi

Subjects
Condensed Matter - Superconductivity
Abstract

The recent realisations of hydrogen doped $Ln$FeAsO ($Ln$=Nd and Sm) superconducting epitaxial thin films call for further investigation of their structural and electrical transport properties. Here, we report on the microstructure of a NdFeAs(O,H) epitaxial thin film and its temperature, field, and orientation dependencies of the resistivity and the critical current density $J_{\rm c}$. The superconducting transition temperature $T_{\rm c}$ is comparable to NdFeAs(O,F). Transmission electron microscopy investigation supported that hydrogen is homogenously substituted for oxygen. A high self-field $J_{\rm c}$ of over 10 MA/cm$^2$ was recorded at 5 K, which is likely to be caused by a short London penetration depth. The anisotropic Ginzburg-Landau scaling for the angle dependence of $J_{\rm c}$ yielded temperature-dependent scaling parameters $\gamma_{\rm J}$ that decreased from 1.6 at 30 K to 1.3 at 5 K. This is opposite to the behaviour of NdFeAs(O,F). Additionally, $\gamma_{\rm J}$ of NdFeAs(O,H) is smaller than that of NdFeAs(O,F). Our results indicate that heavily electron doping by means of hydrogen substitution for oxygen in $Ln$FeAsO is highly beneficial for achieving high $J_{\rm c}$ with low anisotropy without compromising $T_{\rm c}$, which is favourable for high-field magnet applications., Comment: 17 pages, 6 figures with Supplementary Information, accepted in Scientific Reports

Published
2021
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12. Realization of epitaxial thin films of the superconductor K-doped BaFe$_\text{2}$As$_\text{2}$

Author

Qin, Dongyi, Iida, Kazumasa, Hatano, Takafumi, Saito, Hikaru, Ma, Yiming, Wang, Chao, Hata, Satoshi, Naito, Michio, and Yamamoto, Akiyasu

Subjects
Condensed Matter - Superconductivity
Abstract

The iron-based superconductor Ba$_{1-x}$K$_x$Fe$_\text{2}$As$_\text{2}$ is emerging as a key material for high magnetic field applications owing to the recent developments in superconducting wires and bulk permanent magnets. Epitaxial thin films play important roles in investigating and artificially tuning physical properties; nevertheless, the synthesis of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ epitaxial thin films remained challenging because of the high volatility of K. Herein, we report the successful growth of epitaxial Ba$_{1-x}$K$_x$Fe$_\text{2}$As$_\text{2}$ thin films by molecular-beam epitaxy with employing a combination of fluoride substrates (CaF$_\text{2}$, SrF$_\text{2}$, and BaF$_\text{2}$) and a low growth temperature (350$-$420$^\circ$C). Our epitaxial thin film grown on CaF$_\text{2}$ showed sharp superconducting transition at an onset critical temperature of 36 K, slightly lower than bulk crystals by ~2 K due presumably to the strain effect arising from the lattice and thermal expansion mismatch. Critical current density ($J$$_\text{c}$) determined by the magnetization hysteresis loop is as high as 2.2 MA/cm$^\text{2}$ at 4 K under self-field. In-field $J$$_\text{c}$ characteristics of the film are superior to the bulk crystals. The realization of epitaxial thin films opens opportunities for tuning superconducting properties by epitaxial strain and revealing intrinsic grain boundary transport of Ba$_{1-x}$K$_x$Fe$_\text{2}$As$_\text{2}$., Comment: 9 pages, 8 figures

Published
2020
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14. Point defect states emergence in a plasmonic crystal

Author

Saito, Hikaru, Lourenço-Martins, Hugo, Bonnet, Noémie, Li, Xiaoyan, Lovejoy, Tracy C., Dellby, Niklas, Stéphan, Odile, Kociak, Mathieu, and Tizei, Luiz H. G.

Subjects
Physics - Optics
Abstract

Plasmonic crystals are well known to have band structure including a bandgap, enabling the control of surface plasmon propagation and confinement. The band dispersion relation of bulk crystals has been generally measured by momentum-resolved spectroscopy using far field optical techniques while the defects introduced in the crystals have separately been investigated by near field imaging techniques so far. Particularly, defect related energy levels introduced in the plasmonic band gap have not been observed experimentally. In order to investigate such a localized mode, we performed electron energy-loss spectroscopy (EELS), on a point defect introduced in a plasmonic crystal made up of flat cylinders protruding out of a metal film and arranged on a triangular lattice. The energy level of the defect mode was observed to lie within the full band-gap energy range. This was confirmed by a momentum-resolved EELS measurement of the band gap performed on the same plasmonic crystal. Furthermore, we experimentally and theoretically investigated the emergence of the defect states by starting with a corral of flat cylinders protrusions and adding sequentially additional shells of those in order to eventually forming a plasmonic band-gap crystal encompassing a single point defect. It is demonstrated that a defect-like state already forms with a crystal made up of only two shells., Comment: 11 pages, 3 figures

Published
2019
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16. A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Author

Noguchi, Takaaki, Matsumoto, Toru, Miyake, Akira, Igami, Yohei, Haruta, Mitsutaka, Saito, Hikaru, Hata, Satoshi, Seto, Yusuke, Miyahara, Masaaki, Tomioka, Naotaka, Ishii, Hope A., Bradley, John P., Ohtaki, Kenta K., Dobrică, Elena, Leroux, Hugues, Le Guillou, Corentin, Jacob, Damien, de la Peña, Francisco, Laforet, Sylvain, Marinova, Maya, Langenhorst, Falko, Harries, Dennis, Beck, Pierre, Phan, Thi H. V., Rebois, Rolando, Abreu, Neyda M., Gray, Jennifer, Zega, Thomas, Zanetta, Pierre-M., Thompson, Michelle S., Stroud, Rhonda, Burgess, Kate, Cymes, Brittany A., Bridges, John C., Hicks, Leon, Lee, Martin R., Daly, Luke, Bland, Phil A., Zolensky, Michael E., Frank, David R., Martinez, James, Tsuchiyama, Akira, Yasutake, Masahiro, Matsuno, Junya, Okumura, Shota, Mitsukawa, Itaru, Uesugi, Kentaro, Uesugi, Masayuki, Takeuchi, Akihisa, Sun, Mingqi, Enju, Satomi, Takigawa, Aki, Michikami, Tatsuhiro, Nakamura, Tomoki, Matsumoto, Megumi, Nakauchi, Yusuke, Abe, Masanao, Arakawa, Masahiko, Fujii, Atsushi, Hayakawa, Masahiko, Hirata, Naru, Hirata, Naoyuki, Honda, Rie, Honda, Chikatoshi, Hosoda, Satoshi, Iijima, Yu-ichi, Ikeda, Hitoshi, Ishiguro, Masateru, Ishihara, Yoshiaki, Iwata, Takahiro, Kawahara, Kousuke, Kikuchi, Shota, Kitazato, Kohei, Matsumoto, Koji, Matsuoka, Moe, Mimasu, Yuya, Miura, Akira, Morota, Tomokatsu, Nakazawa, Satoru, Namiki, Noriyuki, Noda, Hirotomo, Noguchi, Rina, Ogawa, Naoko, Ogawa, Kazunori, Okada, Tatsuaki, Okamoto, Chisato, Ono, Go, Ozaki, Masanobu, Saiki, Takanao, Sakatani, Naoya, Sawada, Hirotaka, Senshu, Hiroki, Shimaki, Yuri, Shirai, Kei, Sugita, Seiji, Takei, Yuto, Takeuchi, Hiroshi, Tanaka, Satoshi, Tatsumi, Eri, Terui, Fuyuto, Tsukizaki, Ryudo, Wada, Koji, Yamada, Manabu, Yamada, Tetsuya, Yamamoto, Yukio, Yano, Hajime, Yokota, Yasuhiro, Yoshihara, Keisuke, Yoshikawa, Makoto, Yoshikawa, Kent, Fukai, Ryohta, Furuya, Shizuho, Hatakeda, Kentaro, Hayashi, Tasuku, Hitomi, Yuya, Kumagai, Kazuya, Miyazaki, Akiko, Nakato, Aiko, Nishimura, Masahiro, Soejima, Hiromichi, Suzuki, Ayako I., Usui, Tomohiro, Yada, Toru, Yamamoto, Daiki, Yogata, Kasumi, Yoshitake, Miwa, Connolly, Jr, Harold C., Lauretta, Dante S., Yurimoto, Hisayoshi, Nagashima, Kazuhide, Kawasaki, Noriyuki, Sakamoto, Naoya, Okazaki, Ryuji, Yabuta, Hikaru, Naraoka, Hiroshi, Sakamoto, Kanako, Tachibana, Shogo, Watanabe, Sei-ichiro, and Tsuda, Yuichi

Published
2023
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18. Nonequilibrium spherulitic magnetite in the Ryugu samples

Author

Dobrică, Elena, Ishii, Hope A., Bradley, John P., Ohtaki, Kenta, Brearley, Adrian J., Noguchi, Takaaki, Matsumoto, Toru, Miyake, Akira, Igami, Yohei, Haruta, Mitsutaka, Saito, Hikaru, Hata, Satoshi, Seto, Yusuke, Miyahara, Masaaki, Tomioka, Naotaka, Leroux, Hugues, Le Guillou, Corentin, Jacob, Damien, de la Peña, Francisco, Laforet, Sylvain, Marinova, Maya, Langenhorst, Falko, Harries, Dennis, Beck, Pierre, Phan, Thi H.V., Rebois, Rolando, Abreu, Neyda M., Gray, Jennifer, Zega, Thomas, Zanetta, Pierre-M., Thompson, Michelle S., Stroud, Rhonda, Burgess, Kate, Cymes, Brittany A., Bridges, John C., Hicks, Leon, Lee, Martin R., Daly, Luke, Bland, Phil A., Zolensky, Michael E., Frank, David R., Martinez, James, Tsuchiyama, Akira, Yasutake, Masahiro, Matsuno, Junya, Okumura, Shota, Mitsukawa, Itaru, Uesugi, Kentaro, Uesugi, Masayuki, Takeuchi, Akihisa, Sun, Mingqi, Enju, Satomi, Takigawa, Aki, Michikami, Tatsuhiro, Nakamura, Tomoki, Matsumoto, Megumi, Nakauchi, Yusuke, Yurimoto, Hisayoshi, Okazaki, Ryuji, Yabuta, Hikaru, Naraoka, Hiroshi, Sakamoto, Kanako, Tachibana, Shogo, Yada, Toru, Nishimura, Masahiro, Nakato, Aiko, Miyazaki, Akiko, Yogata, Kasumi, Abe, Masanao, Okada, Tatsuaki, Usui, Tomohiro, Yoshikawa, Makoto, Saiki, Takanao, Tanaka, Satoshi, Terui, Fuyuto, Nakazawa, Satoru, Watanabe, Sei-ichiro, and Tsuda, Yuichi

Published
2023
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21. Selective Growth of ZnO Nanosheets via Ionic Layer Epitaxy for UV Photodetection Application.

Author

Matsumura, Ryunosuke, Kazama, Yuta, Saito, Hikaru, Yasui, Takao, Matsuo, Yasutaka, Nasu, Akira, Kobayashi, Hiroaki, Oka, Sayuki, Khemasiri, Narathon, Yomogida, Yohei, and Nagashima, Kazuki

Abstract

Zinc oxide (ZnO) nanosheets have shown great promise for ultraviolet (UV) photodetectors due to their excellent optoelectronic properties and atomically thin structure. Surfactant-assisted ionic layer epitaxy (ILE) is a simple and scalable technique for synthesizing monolayered ZnO nanosheets; however, the formation of a byproduct is inevitable and detrimental for optoelectronic device applications. This study demonstrates a rational strategy for the selective growth of ZnO nanosheets in ILE growth without byproduct formation. The detailed investigation revealed that the formation of byproducts originates from surfactant-induced heterogeneous nucleation. We found that increasing the surfactant concentration suppresses the byproduct formation by localizing the zinc precursor at the water–air interface and opens a concentration window for promoting nanosheet growth. By precise control of the zinc precursor concentration within the concentration window, a selective growth of ca. 1-nm-thick ZnO nanosheets was successfully achieved. A device composed of a single ZnO nanosheet demonstrated a fast-response UV photodetection (rise time/recovery time = 12.3 ms/24.7 ms), which is shorter than the previously reported ZnO nanosheet devices. [ABSTRACT FROM AUTHOR]

Published
2025
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29. Microscopic slickenside as a record of weak shock metamorphism in the surface layer of asteroid Ryugu.

Author

Miyahara, Masaaki, Noguchi, Takaaki, Matsumoto, Toru, Tomioka, Naotaka, Miyake, Akira, Igami, Yohei, Seto, Yusuke, Haruta, Mitsutaka, Saito, Hikaru, Hata, Satoshi, Ishii, Hope A., Bradley, John P., Ohtaki, Kenta K., Dobrică, Elena, Leroux, Hugues, Le Guillou, Corentin, Jacob, Damien, de la Peña, Francisco, Laforet, Sylvain, and Mouloud, Bahae‐Eddine

Subjects
SHEAR (Mechanics), TRANSMISSION electron microscopy, SCANNING electron microscopy, SURFACE morphology, PHYLLOSILICATES, ASTEROIDS
Abstract

The surface morphology of regolith grains from the C‐type asteroid Ryugu was studied in search of evidence of impact events on the asteroid. Scanning electron microscopy revealed that ~8% of C0105‐042 Ryugu grains have a smooth surface on one side of the grains. One of these grains has striated linear grooves (striations) on its smooth surface. Transmission electron microscopy of the grain showed that a porous fine‐grained Mg‐Fe phyllosilicate assemblage, which is the main component of Ryugu grains, is compacted near the smooth surface. The smooth surface with striations closely resembles a slickenside, a characteristic texture found in terrestrial fault rocks formed by shear deformation. There is no evidence of melting/decomposition in the Mg‐Fe phyllosilicates near the smooth surface, indicating that the shear heating temperature is less than ~1100 K. Assuming that the average length of the striations corresponds to the minimum displacement of the micro‐fault, the shock pressure recorded in the C0105‐042 Ryugu grain is estimated to be <~4.5 GPa by a fault mechanics calculation. The shock pressures of C0105‐042, together with those of C0014 (~2 GPa) and C0055 (>~3.9 GPa) in previous studies suggest that the impact velocities recorded in these grains are < ~0.89–1.63 km s−1. Based on the impact velocities, these grains may record an impact event that occurred when asteroid Ryugu was in the orbit in Main Belt. [ABSTRACT FROM AUTHOR]

Published
2024
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32. Incipient space weathering on asteroid 162173 Ryugu recorded by pyrrhotite

Author

Harries, Dennis, primary, Matsumoto, Toru, additional, Langenhorst, Falko, additional, Noguchi, Takaaki, additional, Miyake, Akira, additional, Igami, Yohei, additional, Haruta, Mitsutaka, additional, Seto, Yusuke, additional, Miyahara, Masaaki, additional, Tomioka, Naotaka, additional, Saito, Hikaru, additional, Hata, Satoshi, additional, Takigawa, Aki, additional, Nakauchi, Yusuke, additional, Tachibana, Shogo, additional, Nakamura, Tomoki, additional, Matsumoto, Megumi, additional, Ishii, Hope A., additional, Bradley, John P., additional, Ohtaki, Kenta, additional, Dobrică, Elena, additional, Leroux, Hugues, additional, Le Guillou, Corentin, additional, Jacob, Damien, additional, de la Peña, Francisco, additional, Laforet, Sylvain, additional, Mouloud, Bahae‐eddine, additional, Marinova, Maya, additional, Beck, Pierre, additional, Phan, Van T. H., additional, Rebois, Rolando, additional, Abreu, Neyda M., additional, Gray, Jennifer, additional, Zega, Thomas, additional, Zanetta, Pierre‐M., additional, Thompson, Michelle S., additional, Stroud, Rhonda, additional, Burgess, Kate, additional, Cymes, Brittany A., additional, Bridges, John C., additional, Hicks, Leon, additional, Lee, Martin R., additional, Daly, Luke, additional, Bland, Phil A., additional, Zolensky, Michael E., additional, Frank, David R., additional, Martinez, James, additional, Tsuchiyama, Akira, additional, Yasutake, Masahiro, additional, Matsuno, Junya, additional, Okumura, Shota, additional, Mitsukawa, Itaru, additional, Uesugi, Kentaro, additional, Uesugi, Masayuki, additional, Takeuchi, Akihisa, additional, Sun, Mingqi, additional, Enju, Satomi, additional, Michikami, Tatsuhiro, additional, Yurimoto, Hisayoshi, additional, Okazaki, Ryuji, additional, Yabuta, Hikaru, additional, Naraoka, Hiroshi, additional, Sakamoto, Kanako, additional, Yada, Toru, additional, Nishimura, Masahiro, additional, Nakato, Aiko, additional, Miyazaki, Akiko, additional, Yogata, Kasumi, additional, Abe, Masanao, additional, Okada, Tatsuaki, additional, Usui, Tomohiro, additional, Yoshikawa, Makoto, additional, Saiki, Takanao, additional, Tanaka, Satoshi, additional, Terui, Fuyuto, additional, Nakazawa, Satoru, additional, Watanabe, Sei‐ichiro, additional, and Tsuda, Yuichi, additional

Published
2024
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36. Diffusion-Dominated Luminescence Dynamics of CsPbBr3 Studied Using Cathodoluminescence and Microphotoluminescence Spectroscopy

Author

Nekita, Sho, primary, Yanagimoto, Sotatsu, additional, Sannomiya, Takumi, additional, Akiba, Keiichirou, additional, Takiguchi, Masato, additional, Sumikura, Hisashi, additional, Takagi, Itsuki, additional, Nakamura, Kazutaka G., additional, Yip, SenPo, additional, Meng, You, additional, Ho, Johnny C., additional, Okuyama, Tetsuya, additional, Murayama, Mitsuhiro, additional, and Saito, Hikaru, additional

Published
2024
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37. In situ investigation of an organic micro‐globule and its mineralogical context within a Ryugu “sand” grain

Author

Phan, Van T. H., primary, Beck, Pierre, additional, Rebois, Rolando, additional, Quirico, Eric, additional, Noguchi, Takaaki, additional, Matsumoto, Toru, additional, Miyake, Akira, additional, Igami, Yohei, additional, Haruta, Mitsutaka, additional, Saito, Hikaru, additional, Hata, Satoshi, additional, Seto, Yusuke, additional, Miyahara, Masaaki, additional, Tomioka, Naotaka, additional, Ishii, Hope A., additional, Bradley, John P., additional, Ohtaki, Kenta K., additional, Dobrică, Elena, additional, Leroux, Hugues, additional, Le Guillou, Corentin, additional, Jacob, Damien, additional, de la Peña, Francisco, additional, Laforet, Sylvain, additional, Marinova, Maya, additional, Langenhorst, Falko, additional, Harries, Dennis, additional, Abreu, Neyda M., additional, Gray, Jennifer, additional, Zega, Thomas, additional, Zanetta, Pierre‐M., additional, Thompson, Michelle S., additional, Stroud, Rhonda, additional, Mathurin, Jérémie, additional, Dazzi, Alexandre, additional, Dartois, Emmanuel, additional, Engrand, Cécile, additional, Burgess, Kate, additional, Cymes, Brittany A., additional, Bridges, John C., additional, Hicks, Leon, additional, Lee, Martin R., additional, Daly, Luke, additional, Bland, Phil A., additional, Zolensky, Michael E., additional, Frank, David R., additional, Martinez, James, additional, Tsuchiyama, Akira, additional, Yasutake, Masahiro, additional, Matsuno, Junya, additional, Okumura, Shota, additional, Mitsukawa, Itaru, additional, Uesugi, Kentaro, additional, Uesugi, Masayuki, additional, Takeuchi, Akihisa, additional, Sun, Mingqi, additional, Enju, Satomi, additional, Takigawa, Aki, additional, Michikami, Tatsuhiro, additional, Nakamura, Tomoki, additional, Matsumoto, Megumi, additional, Nakauchi, Yusuke, additional, Abe, Masanao, additional, Nakazawa, Satoru, additional, Okada, Tatsuaki, additional, Saiki, Takanao, additional, Tanaka, Satoshi, additional, Terui, Fuyuto, additional, Yoshikawa, Makoto, additional, Miyazaki, Akiko, additional, Nakato, Aiko, additional, Nishimura, Masahiro, additional, Usui, Tomohiro, additional, Yada, Toru, additional, Yurimoto, Hisayoshi, additional, Nagashima, Kazuhide, additional, Kawasaki, Noriyuki, additional, Sakamotoa, Naoya, additional, Hoppe, Peter, additional, Okazaki, Ryuji, additional, Yabuta, Hikaru, additional, Naraoka, Hiroshi, additional, Sakamoto, Kanako, additional, Tachibana, Shogo, additional, Watanabe, Sei‐ichiro, additional, and Tsuda, Yuichi, additional

Published
2024
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39. Four‐dimensional‐STEM analysis of the phyllosilicate‐rich matrix of Ryugu samples

Author

Mouloud, Bahae‐eddine, primary, Jacob, Damien, additional, de la Peña, Francisco, additional, Marinova, Maya, additional, Le Guillou, Corentin, additional, Viennet, Jean‐Christophe, additional, Laforet, Sylvain, additional, Leroux, Hugues, additional, Teurtrie, Adrien, additional, Noguchi, Takaaki, additional, Matsumoto, Toru, additional, Miyake, Akira, additional, Igami, Yohei, additional, Haruta, Mitsutaka, additional, Saito, Hikaru, additional, Hata, Satoshi, additional, Seto, Yusuke, additional, Miyahara, Masaaki, additional, Tomioka, Naotaka, additional, Ishii, Hope A., additional, Bradley, John P., additional, Ohtaki, Kenta K., additional, Dobrica, Elena, additional, Langenhorst, Falko, additional, Harries, Dennis, additional, Beck, Pierre, additional, Phan, Thi H. V., additional, Rebois, Rolando, additional, Abreu, Neyda M., additional, Gray, Jennifer, additional, Zega, Thomas, additional, Zanetta, Pierre‐M., additional, Thompson, Michelle S., additional, Stroud, Rhonda, additional, Burgess, Kate, additional, Cymes, Brittany A., additional, Bridges, John C., additional, Hicks, Leon, additional, Lee, Martin R., additional, Daly, Luke, additional, Bland, Phil A., additional, Zolensky, Michael E., additional, Frank, David R., additional, Martinez, James, additional, Tsuchiyama, Akira, additional, Yasutake, Masahiro, additional, Matsuno, Junya, additional, Okumura, Shota, additional, Mitsukawa, Itaru, additional, Uesugi, Kentaro, additional, Uesugi, Masayuki, additional, Takeuchi, Akihisa, additional, Sun, Mingqi, additional, Enju, Satomi, additional, Takigawa, Aki, additional, Michikami, Tatsuhiro, additional, Nakamura, Tomoki, additional, Matsumoto, Megumi, additional, Nakauchi, Yusuke, additional, Abe, Masanao, additional, Nakazawa, Satoru, additional, Okada, Tatsuaki, additional, Saiki, Takanao, additional, Tanaka, Satoshi, additional, Terui, Fuyuto, additional, Yoshikawa, Makoto, additional, Miyazaki, Akiko, additional, Nakato, Aiko, additional, Nishimura, Masahiro, additional, Usui, Tomohiro, additional, Yada, Toru, additional, Yurimoto, Hisayoshi, additional, Nagashima, Kazuhide, additional, Kawasaki, Noriyuki, additional, Sakamotoa, Naoya, additional, Okazaki, Ryuji, additional, Yabuta, Hikaru, additional, Naraoka, Hiroshi, additional, Sakamoto, Kanako, additional, Tachibana, Shogo, additional, Watanabe, Sei‐ichiro, additional, and Tsuda, Yuichi, additional

Published
2024
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43. High tolerance of the superconducting current to large grain boundary angles in potassium-doped BaFe2As2.

Author

Hatano, Takafumi, Qin, Dongyi, Iida, Kazumasa, Gao, Hongye, Guo, Zimeng, Saito, Hikaru, Hata, Satoshi, Shimada, Yusuke, Naito, Michio, and Yamamoto, Akiyasu

Subjects
CRYSTAL grain boundaries, IRON-based superconductors, SUPERCONDUCTING magnets, HIGH temperature superconductors, ELECTRON diffraction, CUPRATES
Abstract

Superconducting magnets based on high-temperature superconductors (HTSs) have become critical components in cutting-edge technologies such as advanced medical applications. In HTSs, weak links of superconductivity are inevitable at high-angle grain boundaries (GBs). Thus, two adjacent grains should be crystallographically aligned within the critical angle (θc), for which the intergrain critical current density (Jc) starts to decrease exponentially. The θc of several iron-based superconductors (IBSs) is larger than that of cuprates. However, the decreases in both θc and intergrain Jc under magnetic fields for IBSs are still substantial, hampering their applications in polycrystalline forms. Here, we report that potassium-doped BaFe2As2 (Ba122:K) exhibits superior GB performance to that of previously reported IBSs. A transport Jc of over 0.1 MA/cm2 across [001]-tilt GBs with misorientation angles up to θGB = 24° was recorded even at 28 K, which is a required level for practical applications. Additionally, even in an applied magnetic field, θc was unaltered, and the decay of the intergrain Jc was small. Our results highlight the exceptional potential of Ba122:K for polycrystalline applications and pave the way for next-generation superconducting magnets. We have fabricated artificial grain boundaries in K-doped BaFe2As2 (Ba122:K), one of the Fe-based superconductors. The crystalline orientation map, acquired through the scanning precession electron diffraction measurements, revealed that spontaneous connectivity modification occurred at the grain boundary, which may mitigate weak-link behavior. Specifically, a self-field critical current density Jc of over 0.1 MA/cm2 across the grain boundary with misorientation angles up to 24° was recorded even at 28 K. This performance surpasses the grain boundary properties of hitherto reported Fe-based superconductors. Our results highlight the exceptional potential of Ba122:K for polycrystalline applications and pave the way for next-generation superconducting magnets. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Phyllosilicates with embedded Fe‐based nanophases in Ryugu and Orgueil.

Author

Leroux, Hugues, Le Guillou, Corentin, Marinova, Maya, Laforet, Sylvain, Viennet, Jean‐Christophe, Mouloud, Bahae‐Eddine, Teurtrie, Adrien, de la Peña, Francisco, Jacob, Damien, Hallatt, Daniel, Fernandez, Mario Pelaez, Troadec, David, Noguchi, Takaaki, Matsumoto, Toru, Miyake, Akira, Igami, Yohei, Haruta, Mitsutaka, Saito, Hikaru, Hata, Satoshi, and Seto, Yusuke

Subjects
SCANNING transmission electron microscopy, SAPONITE, PHYLLOSILICATES, METAL sulfides, PETROLOGY, CARBONACEOUS aerosols
Abstract

Samples were recently collected from the carbonaceous asteroid (162173) Ryugu, by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission. They resemble CI chondrites material, thus showing clear evidence of extensive aqueous alteration attested by the widespread presence of a mixture of serpentine and saponite. We present here a scanning transmission electron microscopy study of the Ryugu dominant lithology of the phyllosilicate matrix at the nanometer scale, which we compare with that of the Orgueil CI chondrite. In both objects, the phyllosilicates are of comparable nature and texture, consisting of a mixture of small‐sized crystallites of serpentine and saponite. At the micrometer scale or less, the texture is an alternation of fine and coarse domains. The fine‐grained regions are dominated by saponite. In Ryugu, they enclose numerous Fe,Ni nanosulfides, whereas in Orgueil, S‐ and Ni‐rich ferrihydrite is abundant. The coarse‐grained regions contain more serpentine and no or little Fe,Ni sulfides or ferrihydrite. Scanning transmission x‐ray microscopy at the Fe‐L3 edge also reveals that iron valency of phyllosilicates is higher and more homogeneous in Orgueil (~70% Fe3+) than in Ryugu (<50% Fe3+). We interpret the observed textures as being mostly a consequence of aqueous alteration, likely resulting from the replacement by phyllosilicates of submicrometric components, initially agglomerated by a primary accretion. The fine‐grained domains may result from the replacement of GEMS (GEMS—glass with embedded metal and sulfides) objects or from other types of nanometric assemblages of silicate and Fe‐based nanophases. On the other hand, the coarse‐grained regions may correspond to the replacement of anhydrous crystalline silicates of the olivine and pyroxene type. The major difference is the presence of Fe,Ni sulfides in Ryugu and of ferrihydrite and higher iron valency of phyllosilicates in Orgueil. This might be due to long‐term terrestrial weathering that would have destabilized the nanosulfides. We also explore an alternative scenario involving more oxidizing hydrothermal conditions on the Orgueil parent body. [ABSTRACT FROM AUTHOR]

Published
2024
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46. Mineralogy and petrology of fine‐grained samples recovered from the asteroid (162173) Ryugu.

Author

Noguchi, Takaaki, Matsumoto, Toru, Miyake, Akira, Igami, Yohei, Haruta, Mitsutaka, Saito, Hikaru, Hata, Satoshi, Seto, Yusuke, Miyahara, Masaaki, Tomioka, Naotaka, Ishii, Hope A., Bradley, John P., Ohtaki, Kenta K., Dobrică, Elena, Leroux, Hugues, Guillou, Corentin Le, Jacob, Damien, de la Peña, Francisco, Laforet, Sylvain, and Mouloud, Bahae‐Eddine

Subjects
SCANNING electron microscopes, SAPONITE, SPACE environment, MAGNESITE, MINERALOGY
Abstract

Samples returned from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 mission revealed that Ryugu is composed of materials consistent with CI chondrites and some types of space weathering. We report detailed mineralogy of the fine‐grained Ryugu samples allocated to our "Sand" team and report additional space weathering features found on the grains. The dominant mineralogy is composed of a fine‐grained mixture of Mg‐rich saponite and serpentine, magnetite, pyrrhotite, pentlandite, dolomite, and Fe‐bearing magnesite. These grains have mineralogy comparable to that of CI chondrites, showing severe aqueous alteration but lacking ferrihydrite and sulfate. These results are similar to previous works on large Ryugu grains. In addition to the major minerals, we also find many minerals that are rare or have not been reported among CI chondrites. Accessory minerals identified are hydroxyapatite, Mg‐Na phosphate, olivine, low‐Ca pyroxene, Mg‐Al spinel, chromite, manganochromite, eskolaite, ilmenite, cubanite, polydymite, transjordanite, schreibersite, calcite, moissanite, and poorly crystalline phyllosilicate. We also show scanning transmission electron microscope and scanning electron microscope compositional maps and images of some space‐weathered grains and severely heated and melted grains. Although our mineralogical results are consistent with that of millimeter‐sized grains, the fine‐grained fraction is best suited to investigate impact‐induced space weathering. [ABSTRACT FROM AUTHOR]

Published
2024
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47. Can People Sense Their Personalities Only by Watching the Movements of Their Skeleton in Street Dancing Performances?

Author

Saito, Hikaru, Maki, Yoshiki, Tsuchiya, Shunki, Nakamura, Satoshi, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Weikum, Gerhard, Series Editor, and Kurosu, Masaaki, editor

Published
2018
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49. Factors Affecting the Second Complete Atypical Femoral Fracture after the First Atypical Fracture

Author

Tsuchie, Hiroyuki, primary, Kasukawa, Yuji, additional, Nozaka, Koji, additional, Kinoshita, Hayato, additional, Sasaki, Ken, additional, Aizawa, Toshiaki, additional, Mita, Motoki, additional, Ouchi, Kentaro, additional, Yuasa, Yusuke, additional, Miura, Takanori, additional, Tomite, Takenori, additional, Maekawa, Shigeto, additional, Abe, Hidekazu, additional, Akagawa, Manabu, additional, Shibata, Nobusuke, additional, Fujii, Masashi, additional, Takeshima, Masaaki, additional, Inoue, Jyunichi, additional, Saito, Hikaru, additional, and Miyakoshi, Naohisa, additional

Published
2023
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50. Mineralogy and petrology of fine‐grained samples recovered from the asteroid (162173) Ryugu

Author

Noguchi, Takaaki, primary, Matsumoto, Toru, additional, Miyake, Akira, additional, Igami, Yohei, additional, Haruta, Mitsutaka, additional, Saito, Hikaru, additional, Hata, Satoshi, additional, Seto, Yusuke, additional, Miyahara, Masaaki, additional, Tomioka, Naotaka, additional, Ishii, Hope A., additional, Bradley, John P., additional, Ohtaki, Kenta K., additional, Dobrică, Elena, additional, Leroux, Hugues, additional, Guillou, Corentin Le, additional, Jacob, Damien, additional, de la Peña, Francisco, additional, Laforet, Sylvain, additional, Mouloud, Bahae‐Eddine, additional, Marinova, Maya, additional, Langenhorst, Falko, additional, Harries, Dennis, additional, Beck, Pierre, additional, Phan, Thi H. V., additional, Rebois, Rolando, additional, Abreu, Neyda M., additional, Gray, Jennifer, additional, Zega, Thomas, additional, Zanetta, Pierre‐M., additional, Thompson, Michelle S., additional, Stroud, Rhonda, additional, Burgess, Kate, additional, Cymes, Brittany A., additional, Bridges, John C., additional, Hicks, Leon, additional, Lee, Martin R., additional, Daly, Luke, additional, Bland, Phil A., additional, Smith, William A., additional, McFadzean, Sam, additional, Martin, Pierre‐Etienne, additional, Bagot, Paul A. J., additional, Fougerouse, Dennis, additional, Saxey, David W., additional, Reddy, Steven, additional, Rickard, William D. A., additional, Zolensky, Michael E., additional, Frank, David R., additional, Martinez, James, additional, Tsuchiyama, Akira, additional, Yasutake, Masahiro, additional, Matsuno, Junya, additional, Okumura, Shota, additional, Mitsukawa, Itaru, additional, Uesugi, Kentaro, additional, Uesugi, Masayuki, additional, Takeuchi, Akihisa, additional, Sun, Mingqi, additional, Enju, Satomi, additional, Takigawa, Aki, additional, Michikami, Tatsuhiro, additional, Nakamura, Tomoki, additional, Matsumoto, Megumi, additional, Nakauchi, Yusuke, additional, Abe, Masanao, additional, Nakazawa, Satoru, additional, Okada, Tatsuaki, additional, Saiki, Takanao, additional, Tanaka, Satoshi, additional, Terui, Fuyuto, additional, Yoshikawa, Makoto, additional, Miyazaki, Akiko, additional, Nakato, Aiko, additional, Nishimura, Masahiro, additional, Usui, Tomohiro, additional, Yada, Toru, additional, Yurimoto, Hisayoshi, additional, Nagashima, Kazuhide, additional, Kawasaki, Noriyuki, additional, Sakamotoa, Naoya, additional, Hoppe, Peter, additional, Okazaki, Ryuji, additional, Yabuta, Hikaru, additional, Naraoka, Hiroshi, additional, Sakamoto, Kanako, additional, Tachibana, Shogo, additional, Watanabe, Sei‐ichiro, additional, and Tsuda, Yuichi, additional

Published
2023
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