Disclosure of hidden magnetic moments in low and high T-c hysteretic and semi-reversible type II superconductors during warming to T-c


LeBlanc M., LeBlanc D., Cameron D., Celebi S.

SUPERCONDUCTOR SCIENCE & TECHNOLOGY, vol.13, no.2, pp.109-126, 2000 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 2
  • Publication Date: 2000
  • Doi Number: 10.1088/0953-2048/13/2/301
  • Title of Journal : SUPERCONDUCTOR SCIENCE & TECHNOLOGY
  • Page Numbers: pp.109-126

Abstract

We report on measurements of the evolution of the magnetization [M] upon warming from T-0 (4.2 or 77 K) to T-c for type II superconductors with the locus of [M] initially situated along bridges between the envelopes of the major hysteresis curves. Strongly hysteretic and semi-reversible specimens of low and high T-c type II superconductors have been studied (Nb3Zr, VTi, YBCO, Nb and BiSCCO). Concentric, oppositely directed magnetic moments coexist in the specimens when [M] lies along the bridges. We focused on the cases where [M] = 0, hence, before warming, the constituent moments cancel each other exactly. Since they diminish in magnitude at different rates as T is increased to T-c, their sequential 'release' leads to a rich variety of phenomena. A simple model exploiting the critical state, an equilibrium Meissner current and conservation of flux accounts for all the intricate behaviour encountered.