Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion

Masaki Mito, Yuichiro Kitamura, Takayuki Tajiri, Kazuma Nakamura, Ryo Shiraishi, Kazuma Ogata, Hiroyuki Deguchi, Tomiko Yamaguchi, Nao Takeshita, Terukazu Nishizaki, Kaveh Edalati, Zenji Horita

研究成果: ジャーナルへの寄稿記事

2 引用 (Scopus)

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 T c 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 T c 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 T c 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 T c 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), T c 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 T c at low pressures.

元の言語英語
記事番号125901
ジャーナルJournal of Applied Physics
125
発行部数12
DOI
出版物ステータス出版済み - 3 28 2019

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pressure effects
niobium
hydrostatic pressure
torsion
shear strain
symmetry
low pressure
grain size
transition temperature
cells
energy

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

これを引用

Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion. / Mito, Masaki; Kitamura, Yuichiro; Tajiri, Takayuki; Nakamura, Kazuma; Shiraishi, Ryo; Ogata, Kazuma; Deguchi, Hiroyuki; Yamaguchi, Tomiko; Takeshita, Nao; Nishizaki, Terukazu; Edalati, Kaveh; Horita, Zenji.

:: Journal of Applied Physics, 巻 125, 番号 12, 125901, 28.03.2019.

研究成果: ジャーナルへの寄稿記事

Mito, M, Kitamura, Y, Tajiri, T, Nakamura, K, Shiraishi, R, Ogata, K, Deguchi, H, Yamaguchi, T, Takeshita, N, Nishizaki, T, Edalati, K & Horita, Z 2019, 'Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion', Journal of Applied Physics, 巻. 125, 番号 12, 125901. https://doi.org/10.1063/1.5083094
Mito, Masaki ; Kitamura, Yuichiro ; Tajiri, Takayuki ; Nakamura, Kazuma ; Shiraishi, Ryo ; Ogata, Kazuma ; Deguchi, Hiroyuki ; Yamaguchi, Tomiko ; Takeshita, Nao ; Nishizaki, Terukazu ; Edalati, Kaveh ; Horita, Zenji. / Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion. :: Journal of Applied Physics. 2019 ; 巻 125, 番号 12.
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