水素吸蔵合金PdDxにおける不均一な超伝導状態

URI http://harp.lib.hiroshima-u.ac.jp/it-hiroshima/metadata/12291
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Title
水素吸蔵合金PdDxにおける不均一な超伝導状態
Title Alternative
Inhomogeneous superconducting state in hydrogen storage alloy PdDx
Author
氏名 安塚 周磨
ヨミ ヤスズカ シュウマ
別名 Yasuzuka Syuma
Subject
palladium
hydrogen
superconductivity
Josephson junction
inhomogeneity
optical phonon
Abstract

Disorder affects the coherent state of a superconductor in characteristic ways. In conventional superconductors with s-wave pairing symmetry, magnetic defects act as strong pair breakers, whereas nonmagnetic defects have negligible effect. In this review, we will show that nonmagnetic defects promote the superconductivity mediated by optical phonon in palladium-hydride system. Temperature dependence of the critical current is well fitted by the Ambegaokar-Baratoff relation, suggesting the existence of Josephson junction between the superconducting(SC) grains. Appearance of the coherent SC grains through the Josephson coupling may be associated with the interaction between deuterium and lattice defects such as vacancies and dislocations. In addition, we theoretically investigated whether or not optical phonon modes formed by the collective motion of a large number of atoms exist in nonstoichiometric PdHx, possessing random or inhomogeneous lattices. We found that individual excitations compete with collective excitations in controlling the system’s randomness, and that optical phonons develop from localized phonon modes as the stoichiometry x increases.

Journal Title
広島工業大学紀要. 研究編
Volume
53
Spage
185
Epage
190
Published Date
2019-02
Publisher
広島工業大学
ISSN
1346-9975
NCID
AA11599110
Language
jpn
NIIType
Departmental Bulletin Paper
Text Version
出版社版
Rights
publisher
Set
it-hiroshima