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Journal Articles

New antiferromagnetic order with pressure-induced superconductivity in EuFe$$_2$$As$$_2$$

Ikeda, 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

 Percentile:100(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 EuFe$$_2$$As$$_2$$ superconductor in the pressure range from 2.4 to 3.0 GPa by $$^{57}$$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 $$^{57}$$Fe NFS spectra reveals that the new antiferromagnetic order develops with the superconductivity. This non-trivial coupling of two ordered states in EuFe$$_2$$As$$_2$$ under pressure demonstrates a new and intriguing relationship between magnetism and superconductivity in Fe-based superconductors.

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:1 Percentile:17.79

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:3 Percentile:10.17

Journal Articles

$$^{61}$$Ni synchrotron radiation-based M$"o$ssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, 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:5 Percentile:50.18(Multidisciplinary Sciences)

Journal Articles

Attempt to measure magnetic hyperfine fields in metallic thin wires under spin Hall conditions using synchrotron-radiation M$"o$ssbauer spectroscopy

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:82.81(Physics, Applied)

Journal Articles

Silicon avalanche photodiode linear-array detector with multichannel scaling system for pulsed synchrotron X-ray experiments

Kishimoto, Shunji*; Mitsui, Takaya; Haruki, Rie*; Yoda, Yoshitaka*; Taniguchi, Takashi*; Shimazaki, Shoichi*; Ikeno, Masahiro*; Saito, Masatoshi*; Tanaka, Masanobu*

Journal of Instrumentation (Internet), 10(5), p.C05030_1 - C05030_6, 2015/05

 Times Cited Count:5 Percentile:55.5(Instruments & Instrumentation)

Journal Articles

Nuclear resonant scattering measurements on $$^{57}$$Fe by multichannel scaling with a 64 pixel silicon avalanche photodiode linear-array detector

Kishimoto, Shunji*; Mitsui, Takaya; Haruki, Rie*; Yoda, Yoshitaka*; Taniguchi, Takashi*; Shimazaki, Shoichi*; Ikeno, Masahiro*; Saito, Masatoshi*; Tanaka, Masanobu*

Review of Scientific Instruments, 85(11), p.113102_1 - 113102_5, 2014/11

 Times Cited Count:5 Percentile:60.1(Instruments & Instrumentation)

Journal Articles

Development of $$^{125}$$Te synchrotron-radiation-based M$"o$ssbauer spectroscopy

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:2 Percentile:30.92

Journal Articles

$$^{125}$$Te synchrotron-radiation-based M$"o$ssbauer spectroscopy of Fe$$_{1.1}$$Te and FeTe$$_{0.5}$$Se

Kurokuzu, 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

 Percentile:100(Physics, Multidisciplinary)

Journal Articles

Synchrotron radiation-based M$"o$ssbauer spectra of $$^{174}$$Yb measured with internal conversion electrons

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:9 Percentile:45.24(Physics, Applied)

A detection system for synchrotron-radiation (SR)-based M$"o$ssbauer 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 M$"o$ssbauer spectrum using the 76.5 keV level of $$^{174}$$Yb was observed without $$^{174}$$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 M$"o$ssbauer 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.

Journal Articles

Observation of a pressure-induced As-As hybridization associated with a change in the electronic state of Fe in the tetragonal phase of EuFe$$_2$$As$$_2$$

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:7 Percentile:54.93(Physics, Condensed Matter)

The electronic and vibrational properties of EuFe$$_2$$As$$_2$$ in the tetragonal phase between 0 and 5 GPa have been investigated using $$^{57}$$Fe M$"o$ssbauer spectroscopy and $$^{57}$$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$$_4$$ 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 EuFe$$_2$$As$$_2$$, 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 AFe$$_2$$As$$_2$$.

Journal Articles

Orthorhombic fluctuations in tetragonal $$A$$Fe$$_2$$2As$$_2$$ ($$A$$ = Sr and Eu)

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:7 Percentile:59.49(Materials Science, Multidisciplinary)

The structural and magnetic phase transition in $$A$$Fe$$_2$$As$$_2$$ ($$A$$ = Sr and Eu) was investigated from the viewpoint of the Fe-specific phonon density of states, $$g$$$$^{e}$$$$_{rm Fe}$$($$E$$), utilizing $$^{57}$$Fe nuclear resonant inelastic-scattering and ab initio phonon calculations. The Fe optical phonon branches in $$g$$$$^{e}$$$$_{rm Fe}$$($$E$$) around 25 meV show no anomalies across the phase transition temperature, $$T_{rm SDW}$$, with decreasing temperature. Meanwhile, the peak intensity around 32 meV decreases and increases at 1.25$$T_{rm SDW}$$ and $$T_{rm SDW}$$, 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 $$T_{rm SDW}$$, suggesting softening in some of the sound waves. Our results indicate the presence of orthorhombic fluctuations in tetragonal $$A$$Fe$$_2$$As$$_2$$.

Journal Articles

Structural and valence changes of europium hydride induced by application of high-pressure H$$_{2}$$

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:16 Percentile:27.01(Physics, Multidisciplinary)

Europium-hydride EuH$$_{x}$$ exposed to high-pressure H$$_{2}$$ conditions has been found to exhibit structural and valence changes, $$Pnma$$ ($$x$$=2, divalent) $$rightarrow$$ $$P$$63/$$mmc$$ ($$x$$=2, 7.2-8.7 GPa) $$rightarrow$$ $$I$$4/$$m$$ ($$x$$$$>$$2, 8.7-9.7 GPa) $$rightarrow$$ $$I$$4/$$mmm$$ ($$x$$$$>$$2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the $$I$$4/$$mmm$$ structure is the $$beta$$-phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH$$_{x}$$ is no longer an "irregular" member of the rare earth metal hydrides.

Journal Articles

Investigation on new scintillators for subnanosecond time-resolved X-ray measurements

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:1 Percentile:40.37

Journal Articles

Synchrotron-radiation-based M$"o$ssbauer spectroscopy

Seto, 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:37 Percentile:14.33(Physics, Multidisciplinary)

We have developed a new method that yields M$"o$ssbauer absorption spectra using synchrotron radiation (SR); this method is applicable for almost all M$"o$ssbauer nuclides including those that cannot be measured by previous methods using radioisotope (RI) sources. The M$"o$ssbauer spectrum of the 68.752 keV excited state of $$^{73}$$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 M$"o$ssbauer spectroscopy measurements owing to the excellent features of SR.

Journal Articles

Development of neV-resolution spectroscopy using synchrotron-based $$^{57}$$Fe M$"o$ssbauer radiation

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:8 Percentile:60.83(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 $$^{57}$$FeBO$$_{3}$$ single crystal near the N$'e$el temperature for producing $$^{57}$$Fe M$"o$ssbauer radiation from synchrotron radiation, and a single-line M$"o$ssbauer absorber ($$^{57}$$Fe-enriched stainless steel foil) for analyzing the energy distribution. As a feasibility study, we have performed the measurement of the M$"o$ssbauer 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.

Journal Articles

High-energy-resolution monochromator for nuclear resonant scattering of synchrotron radiation by Te-125 at 35.49 keV

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 $$^{125}$$Te at 35.49 keV using the backscattering of sapphire (9 1 -10 68). The relative energy resolution of $$2.1times10^{-7}$$ 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 $$^{125}$$Te.

Journal Articles

Observation of nuclear excitation of $$^{19}$$F by synchrotron radiation

Harami, Taikan; Yoda, Yoshitaka*; Fujiwara, Mamoru*

Journal of the Physical Society of Japan, 75(12), p.125002_1 - 125002_2, 2006/12

 Times Cited Count:1 Percentile:87.14(Physics, Multidisciplinary)

The nuclear excitation of $$^{19}$$F was first observed by synchrotron radiation in the beamline of SPring-8. The excitation energy, 110 keV, is the highest energy that was observed by synchrotron radiation so far. In spite of the low detector efficiency and the relatively short lifetime of 0.6 ns, the identification of the nuclear excitation was successful. The $$^{19}$$F nuclear excitation will provide a specific tool for the detection, identification and quatification of fluorine-containing drugs. In the field of elementary particle physics, the parity non-consevation effect can now be studied in nuclear excitation processes in $$^{19}$$F.

Journal Articles

Nuclear resonant scattering of synchrotron radiation by Yb nuclides

Masuda, Ryo*; Higashitaniguchi, Satoshi*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Seto, Makoto*; Mitsui, Takaya; Yoda, Yoshitaka*; Haruki, Rie*; Kishimoto, Shunji*

Journal of the Physical Society of Japan, 75(9), p.094716_1 - 094716_4, 2006/09

 Times Cited Count:1 Percentile:87.14(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Flux growth of $$^{57}$$Fe-enriched very high quality iron borate single crystal and observation of magnetic domain structure using X-ray double crystal topography

Mitsui, Takaya; Takei, Fumihiko*; Kitao, Shinji*; Seto, Makoto; Harami, Taikan; Zhang, X.*; Yoda, Yoshitaka*; Kikuta, Seishi*

Transactions of the Materials Research Society of Japan, 30(1), p.7 - 10, 2005/03

no abstracts in English

34 (Records 1-20 displayed on this page)