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D
measured with inelastic neutron spectroscopyYamaura, Junichi*; Hiraka, Haruhiro*; Iimura, Soshi*; Muraba, Yoshinori*; Bang, J.*; Ikeuchi, Kazuhiko*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Honda, Takashi*; Hiraishi, Masatoshi*; et al.
Physical Review B, 99(22), p.220505_1 - 220505_6, 2019/06
Times Cited Count：1 Percentile：10.83(Materials Science, Multidisciplinary)Inelastic neutron scattering was performed for an iron-based superconductor, where most of D (deuterium) replaces oxygen, while a tiny amount goes into interstitial sites. By first-principle calculation, we characterize the interstitial sites for D (and for H slightly mixed) with four equivalent potential minima. Below the superconducting transition temperature Tc = 26 K, new excitations emerge in the range 5-15 meV, while they are absent in the reference system LaFeAsOF. The strong excitations at 14.5 meV and 11.1 meV broaden rapidly around 15 K and 20 K, respectively, where each energy becomes comparable to twice of the superconducting gap. The strong excitations are ascribed to a quantum rattling, or a band motion of hydrogen, which arises only if the number of potential minima is larger than two.
DTamatsukuri, Hiromu*; Hiraka, Haruhiro*; Ikeuchi, Kazuhiko*; Iimura, Soshi*; Muraba, Yoshinori*; Nakamura, Mitsutaka; Sagayama, Hajime*; Yamaura, Junichi*; Murakami, Yoichi*; Kuramoto, Yoshio*; et al.
Physical Review B, 98(17), p.174415_1 - 174415_6, 2018/11
Times Cited Count：2 Percentile：16.65(Materials Science, Multidisciplinary)Magnetic excitations in a heavily electron-doped antiferromagnet, LaFeAsOD, have been investigated using powder inelastic neutron scattering. Unlike other parent compounds of the iron-based superconductors, the magnetic excitation gap in LaFeAsOD was not detected down to the lowest measured temperature of 4 K. This result can be understood as a result of quasi-isotropy within the ab plane, which is consistent with the band calculation result that the 
orbital plays the dominant role in the magnetism of LaFeAsOH. In addition, the intensities of the magnetic excitations in this phase are much stronger than those in nondoped LaFeAsO. Even in the paramagnetic phase, the magnetic excitation in LaFeAsOD persists. These results corroborate recent studies showing that the electron doping enhances the localized nature in this system.
H
Matsuishi, Satoru*; Hanna, Taku*; Muraba, Yoshinori*; Kim, S. W.*; Kim, J. E.*; Takata, Masaki*; Shamoto, Shinichi; Smith, R. I.*; Hosono, Hideo*
Physical Review B, 85(1), p.014514_1 - 014514_6, 2012/01
Times Cited Count：41 Percentile：85.51(Materials Science, Multidisciplinary)We performed the neutron powder diffraction and synchrotron X-ray diffraction measurements on CeFeAsO(D,H) (
= 0.0-0.48) as a representative of 1111-type family of iron-based superconductors LnFeAsOH (
= lanthanoid). These results strongly suggest that H
ions exclusively occupy the oxygen sites in both samples, regardless of the hydrogen species in the starting material.
Hanna, Taku*; Muraba, Yoshinori*; Matsuishi, Satoru*; Igawa, Naoki; Kodama, Katsuaki; Shamoto, Shinichi; Hosono, Hideo*
Physical Review B, 84(2), p.024521_1 - 024521_7, 2011/07
Times Cited Count：91 Percentile：94.9(Materials Science, Multidisciplinary)
