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Yamaura, 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:4 Percentile:17.90(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.
Tamatsukuri, 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:3 Percentile:13.43(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 LaFeAsO
D
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 LaFeAsO
H
. 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 LaFeAsO
D
persists. These results corroborate recent studies showing that the electron doping enhances the localized nature in this system.
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:47 Percentile:83.30(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 LnFeAsO
H
(
= 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:106 Percentile:94.46(Materials Science, Multidisciplinary)