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Tsutsui, Satoshi; Higashinaka, Ryuji*; Nakamura, Raito*; Fujiwara, Kosuke*; Nakamura, Jin*; Kobayashi, Yoshio*; Ito, Takashi; Yoda, Yoshitaka*; Kato, Kazuo*; Nitta, Kiyofumi*; et al.
Hyperfine Interactions, 242(1), p.32_1 - 32_10, 2021/12
Times Cited Count:1 Percentile:84.42Nagao, Michihiro*; Kelley, E. G.*; Faraone, A.*; Saito, Makina*; Yoda, Yoshitaka*; Kurokuzu, Masayuki*; Takata, Shinichi; Seto, Makoto*; Butler, P. D.*
Physical Review Letters, 127(7), p.078102_1 - 078102_7, 2021/08
Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count:13 Percentile:99.28Ikeda, Shugo*; Tsuchiya, Yu*; Zhang, X.-W.*; Kishimoto, Shunji*; Kikegawa, Takumi*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko; Glasbrenner, J.*; Kobayashi, Hisao*
Physical Review B, 98(10), p.100502_1 - 100502_6, 2018/09
Times Cited Count:4 Percentile:26.15(Materials Science, Multidisciplinary)The interplay between magnetism and superconductivity is one of important subjects to investigate the pairing mechanism in novel superconductors. We have found new coexistence between an antiferromagnetic order in the Fe sublattice and superconductivity of the FeAs-based EuFeAs superconductor in the pressure range from 2.4 to 3.0 GPa by Fe nuclear forward scattering (NFS) using a single crystal sample. The magnetic state in the Fe sublattice changes to a new antiferromagnetic one with superconductivity from a stripe-type antiferromagnetic one observed in normal conducting state at 2.7 GPa. Below the superconducting transition temperature, the temperature dependence of Fe NFS spectra reveals that the new antiferromagnetic order develops with the superconductivity. This non-trivial coupling of two ordered states in EuFeAs under pressure demonstrates a new and intriguing relationship between magnetism and superconductivity in Fe-based superconductors.
Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Times Cited Count:3 Percentile:86.59Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count:7 Percentile:91.29Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.
Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02
Times Cited Count:8 Percentile:41.01(Multidisciplinary Sciences)Mibu, Ko*; Mitsui, Takaya; Tanaka, Masaaki*; Masuda, Ryo*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Yoda, Yoshitaka*; Seto, Makoto*
Journal of Applied Physics, 117(17), p.17E126_1 - 17E126_4, 2015/05
Times Cited Count:2 Percentile:9.19(Physics, Applied)Kishimoto, Shunji*; Mitsui, Takaya; Haruki, Rie*; Yoda, Yoshitaka*; Taniguchi, Takashi*; Shimazaki, Shoichi*; Ikeno, Masahiro*; Saito, Masatoshi*; Tanaka, Manobu*
Journal of Instrumentation (Internet), 10(5), p.C05030_1 - C05030_6, 2015/05
Times Cited Count:6 Percentile:28.47(Instruments & Instrumentation)Kishimoto, Shunji*; Mitsui, Takaya; Haruki, Rie*; Yoda, Yoshitaka*; Taniguchi, Takashi*; Shimazaki, Shoichi*; Ikeno, Masahiro*; Saito, Masatoshi*; Tanaka, Manobu*
Review of Scientific Instruments, 85(11), p.113102_1 - 113102_5, 2014/11
Times Cited Count:8 Percentile:36.91(Instruments & Instrumentation)Kurokuzu, Masayuki*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Saito, Makina*; Masuda, Ryo*; Mitsui, Takaya; Yoda, Yoshitaka*; Seto, Makoto*
Hyperfine Interactions, 226(1), p.687 - 691, 2014/04
Times Cited Count:3 Percentile:70.01Kurokuzu, Masayuki*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Saito, Makina*; Masuda, Ryo*; Mitsui, Takaya; Yoda, Yoshitaka*; Seto, Makoto*
Journal of the Physical Society of Japan, 83(4), p.044708_1 - 044708_4, 2014/04
Times Cited Count:2 Percentile:20.48(Physics, Multidisciplinary)Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Iga, Fumitoshi*; Seto, Makoto
Applied Physics Letters, 104(8), p.082411_1 - 082411_5, 2014/02
Times Cited Count:19 Percentile:63.84(Physics, Applied)A detection system for synchrotron-radiation (SR)-based Mssbauer spectroscopy was developed to enhance the nuclear resonant scattering counting rate and thus increase the available nuclides. In the system, a windowless avalanche photodiode (APD) detector was combined with a vacuum cryostat to detect the internal conversion (IC) electrons and fluorescent X-rays accompanied by nuclear de-excitation. As a feasibility study, the SR-based Mssbauer spectrum using the 76.5 keV level of Yb was observed without Yb enrichment of the samples. The counting rate was five times higher than that of our previous system, and the spectrum was obtained within 10 h. This result shows that nuclear resonance events can be more efficiently detected by counting IC electrons for nuclides with high IC coefficients. Furthermore, the windowless detection system enables us to place the sample closer to the APD elements and is advantageous for nuclear resonant inelastic scattering measurements. Therefore, this detection system can not only increase the number of nuclides accessible in SR-based Mssbauer spectroscopy but also allows the nuclear resonant inelastic scattering measurements of small single crystals or enzymes with dilute probe nuclides that are difficult to measure with the previous detection system.
Kobayashi, Hisao*; Ikeda, Shugo*; Sakaguchi, Yui*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko
Journal of Physics; Condensed Matter, 25(2), p.022201_1 - 022201_6, 2013/01
Times Cited Count:9 Percentile:40.49(Physics, Condensed Matter)The electronic and vibrational properties of EuFeAs in the tetragonal phase between 0 and 5 GPa have been investigated using Fe Mssbauer spectroscopy and Fe nuclear resonance inelastic scattering, respectively. We find a discontinuous increase of the center shift around 2.3 GPa, reflecting a change of the electronic state of Fe, and above 2.5 GPa a softening of the optical phonon modes associated with an increase of the relative volume of the FeAs tetrahedron in the unit cell. Our findings reveal that an effective As-As hybridization along the c axis appears at approximately 2.3 GPa in the tetragonal phase of EuFeAs, along with a change in the electronic state of Fe, causing bulk superconductivity to appear at a low temperature. Consequently, the change in the electronic state of the Fe atom and the effective As-As hybridization play key roles in the pressure-induced superconductivity in the tetragonal phase of AFeAs.
Kobayashi, Hisao*; Ikeda, Shugo*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko
Physical Review B, 84(18), p.184304_1 - 184304_7, 2011/11
Times Cited Count:9 Percentile:39.45(Materials Science, Multidisciplinary)The structural and magnetic phase transition in FeAs ( = Sr and Eu) was investigated from the viewpoint of the Fe-specific phonon density of states, (), utilizing Fe nuclear resonant inelastic-scattering and ab initio phonon calculations. The Fe optical phonon branches in () around 25 meV show no anomalies across the phase transition temperature, , with decreasing temperature. Meanwhile, the peak intensity around 32 meV decreases and increases at 1.25 and , respectively, which originates from phonon branches involving Fe and As atomic displacements in the tetragonal structure. This decrease is related to the phonon branches involving atomic displacements in the ab plane. Furthermore, the average sound velocity below 8 meV shows no temperature dependence down to , suggesting softening in some of the sound waves. Our results indicate the presence of orthorhombic fluctuations in tetragonal FeAs.
Matsuoka, Takahiro*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Mitsui, Takaya; Masuda, Ryo; Seto, Makoto*; Yoda, Yoshitaka*; Shimizu, Katsuya*; Machida, Akihiko; et al.
Physical Review Letters, 107(2), p.025501_1 - 025501_4, 2011/07
Times Cited Count:27 Percentile:77.69(Physics, Multidisciplinary)Europium-hydride EuH exposed to high-pressure H conditions has been found to exhibit structural and valence changes, (=2, divalent) 63/ (=2, 7.2-8.7 GPa) 4/ (2, 8.7-9.7 GPa) 4/ (2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the 4/ structure is the -phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH is no longer an "irregular" member of the rare earth metal hydrides.
Haruki, Rie; Shibuya, Kengo*; Nishikido, Fumihiko*; Koshimizu, Masanori*; Yoda, Yoshitaka*; Kishimoto, Shunji*
Journal of Physics; Conference Series, 217, p.012007_1 - 012007_4, 2010/05
Times Cited Count:4 Percentile:81.66Seto, Makoto; Masuda, Ryo; Higashitaniguchi, Satoshi*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Inaba, Chika*; Mitsui, Takaya; Yoda, Yoshitaka*
Physical Review Letters, 102(21), p.217602_1 - 217602_4, 2009/05
Times Cited Count:55 Percentile:87.94(Physics, Multidisciplinary)We have developed a new method that yields Mssbauer absorption spectra using synchrotron radiation (SR); this method is applicable for almost all Mssbauer nuclides including those that cannot be measured by previous methods using radioisotope (RI) sources. The Mssbauer spectrum of the 68.752 keV excited state of Ge, which cannot be measured using a RI source, was measured using SR. Our results show that this method can be used to perform advanced Mssbauer spectroscopy measurements owing to the excellent features of SR.
Masuda, Ryo; Mitsui, Takaya; Kitao, Shinji*; Higashitaniguchi, Satoshi*; Yoda, Yoshitaka*; Seto, Makoto
Japanese Journal of Applied Physics, 47(10), p.8087 - 8090, 2008/10
Times Cited Count:12 Percentile:44.67(Physics, Applied)A synchrotron-radiation-based neV-resolution spectrometer has been developed using single-line pure nuclear Bragg reflection. The developed optical system consists of two components: a FeBO single crystal near the Nel temperature for producing Fe Mssbauer radiation from synchrotron radiation, and a single-line Mssbauer absorber (Fe-enriched stainless steel foil) for analyzing the energy distribution. As a feasibility study, we have performed the measurement of the Mssbauer radiation diffracted by a Si crystal under ultrasound vibration with the optical system and have successfully observed the neV-range energy modulation due to the ultrasound vibration.
Imai, Yasuhiko*; Yoda, Yoshitaka*; Kitao, Shinji*; Masuda, Ryo; Higashitaniguchi, Satoshi*; Inaba, Chika*; Seto, Makoto
Advances in X-ray/EUV Optics and Components II (Proceedings of SPIE Vol.6705), p.670512_1 - 670512_7, 2007/00
We have developed a high-resolution monochromator (HRM) for the measurement of nuclear resonant scattering of synchrotron radiation by Te at 35.49 keV using the backscattering of sapphire (9 1 -10 68). The relative energy resolution of is achieved, that is 7.5 meV in energy bandwidth. A new HRM has been desired at this energy region because of the low efficiency of usual Si HRMs. This HRM opens studies on element-specific dynamics and electronic state of substances containing Te.