Nonsaturated pinning characteristics by normal precipitates in superconducting NbTa

✍ Scribed by T. Matsushita; N. Harada; K. Yamafuji

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 532 KB
• Volume: 29
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(89)90181-1

✦ Synopsis

Nonsaturated pinning characteristics and elastic and plastic properties of a fluxoid lattice were measured by an a.c. inductive method for superconducting Nb-Ta tapes with normal Nb2N precipitates. The Labusch parameter characterizing an elastic constant of the pinned fluxoid lattice decreased fairly linearly with increasing magnetic field, and increased with increasing volume fraction of normal precipitates. The interaction distance, the maximum reversible displacement at the yield point, was kept nearly constant or increased up to a vicinity of the upper critical field for strongly pinned specimens. This behaviour in the interaction distance, which is quite different from the case of saturation, suggests that the defective fluxoid lattice is stabilized by strong pinning interactions. The dependence of the macroscopic pinning force on the pinning parameters estimated from electron micrographs was also investigated. It seems to agree with the linear summation theory better than the Larkin-Ovchinnikov theory.