Critical temperature in bulk ultrafine-grained superconductors of Nb, V, and Ta processed by high-pressure torsion

Terukazu Nishizaki, Kaveh Edalati, Seungwon Lee, Zenji Horita, Tadahiro Akune, Tsutomu Nojima, Satoshi Iguchi, Takahiko Sasaki

Research output: Contribution to journalReview article

Abstract

This overview describes the progressive results of the superconducting critical temperature in bulk nanostructured metals (niobium, vanadium and tantalum) processed by high-pressure torsion (HPT). Bulk nanostructured superconductors provide a new route to control superconducting property, because ultrafine-grain structures with a high density of grain boundaries, dislocations, and other crystalline defects modify the superconducting order parameter. The critical temperature Tc in Nb increases with the evolution of grain refinement owing to the quantum confinement of electrons in ultrafine grains. In V and Ta, however, Tc decreases at a certain HPT revolution number (i.e. at certain strain levels). The different behaviour of Tc in the three materials is explained by the competition effect between the quantum size effect and disorder effect; these effects are characterized by the parameters of grain size, electron mean free path, and superconducting coherence length.

Original languageEnglish
Pages (from-to)1367-1376
Number of pages10
JournalMaterials Transactions
Volume60
Issue number7
DOIs
Publication statusPublished - Jan 1 2019

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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