Doping-dependent Fe phonon dynamics in LaFeAsOH studied by Fe nuclear resonant inelastic scattering

Kawachi, Shiro*; Hiraka, Haruhiro*; Yamaura, Junichi*; Iimura, Soshi*; Nakamura, Hiroki; Tsutsui, Satoshi*; Yoda, Yoshitaka*; Machida, Masahiko; Hosono, Hideo*; Kobayashi, Hisao*

Physical Review B, 113(2), p.024519_1 - 024519_7, 2026/01

https://doi.org/10.1103/7zd9-5t9z

To investigate the phonon dynamics of iron in the heavily hydride-ion-substituted region of LaFeAsOH (), Fe nuclear resonant inelastic scattering measurements were performed over a wide temperature range from 5 to 300 K on two polycrystalline samples with and 0.51, which exhibit superconducting and antiferromagnetic ground states, respectively. The resulting inelastic scattering spectra revealed distinct differences between the two compositions. The Fe phonon density of states (PDOS) exhibits a pronounced peak at 15 meV for , whereas this peak is absent in . Density functional theory calculations support the interpretation that the PDOS peak at 15 meV is associated with the optical vibrational modes of Fe atoms along the nearest-neighbor direction, mediated by As atoms. The calculations further suggest that the suppression of the PDOS peak at 15 meV for originates from in-plane electronic inequivalence. These findings suggest that signatures of electronic nematicity may persist over a wide temperature range in the composition, which exhibits magnetic and structural order, whereas such signatures are almost absent in the superconducting composition.

Sm synchrotron-radiation-based Mssbauer and SR studies of SmRuGe

Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

https://doi.org/10.1007/s10751-024-01900-6

Relationship between viscosity and acyl tail dynamics in lipid bilayers

Nagao, 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

https://doi.org/10.1103/PhysRevLett.127.078102

New antiferromagnetic order with pressure-induced superconductivity in EuFeAs

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

https://doi.org/10.1103/PhysRevB.98.100502

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.

New muonium HFS measurements at J-PARC/MUSE

Strasser, 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

https://doi.org/10.1007/s10751-016-1331-4

Attempt to measure magnetic hyperfine fields in metallic thin wires under spin Hall conditions using synchrotron-radiation Mssbauer 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

https://doi.org/10.1063/1.4917189

Nuclear resonant scattering measurements on 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, Manobu*

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

https://doi.org/10.1063/1.4900862

Te synchrotron-radiation-based Mssbauer spectroscopy of FeTe and FeTeSe

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

https://doi.org/10.7566/JPSJ.83.044708

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

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

https://doi.org/10.1088/0953-8984/25/2/022201

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.

Structural and valence changes of europium hydride induced by application of high-pressure H

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

https://doi.org/10.1103/PhysRevLett.107.025501

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.