Kyushu Institute of Technology Academic Repository
Kyutacarは九州工業大学で生産された研究成果を オープンアクセスで提供する機関リポジトリシステムです。 Kyutacar is open-access repository of research by members of the Kyushu Institute of Technology.
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan
Department of Electrical Engineering, Kyushu Sangyo University, Fukuoka 813-8503, Japan
Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
抄録
We study the effects of hydrostatic pressure (HP) compression on the superconducting transition of severely strained Nb samples, whose grain sizes are reduced to the submicrometer level. Engineered granularity by high-pressure torsion (HPT) treatment changes the strength of coupling between submicrometer-scale grains and introduces lattice strain. We attempt to utilize the initially accumulated shear strain in the starting material for increasing the superconducting transition temperature Tc under HP compression. The HP effects on non-strained Nb have already been investigated in the pressure regime over 100 GPa by Struzhkin et al. [Phys. Rev. Lett. 79, 4262 (1997)], and Tc reportedly exhibited an increase from 9.2 to 9.9 K at approximately 10 GPa. (1) Slightly strained Nb in the HPT treatment exhibits the increase in Tc under HP due to the strengthening of the intergrain coupling, so the pressure scale of the pressure response observed by Struzhkin et al. is reduced to approximately one-seventh at the maximum. (2) Prominently strained Nb in the HPT treatment exhibits the increase in Tc under HP due to a reduction in structural symmetry at the unit-cell level: In a Nb sample subjected to HPT (6 GPa, 10 revolutions), Tc exceeds 9.9 K at approximately 2 GPa. According to our first-principle calculations, the reduction in the structural symmetry affords an increase in the density of states at the Fermi energy, thereby yielding a prominent increase in Tc at low pressures.
雑誌名
Journal of Applied Physics
巻
125
号
12
ページ
125901-1 - 125901-13
発行年
2019-03-22
出版者
AIP Publishing
ISSN
0021-8979
1089-7550
書誌レコードID
AA00693547
DOI
https://doi.org/10.1063/1.5083094
権利
Copyright (c) 2019 Author(s)
The following article has been submitted to/accepted by Journal of Applied Physics. After it is published, it will be found at https://aip.scitation.org/journal/jap.
Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion
scunit-2018_20.pdf
(5.25MB)
