Thermal Release of Hidden Magnetic Moments in High T_c Bi:2223/Ag Superconducting Tape During Warming to T_c

摘要

We report on measurements of the evolution of the magnetization , upon warming from To (77 K) to T_c, for Bi:2223/Ag tape prepared by the continuous filling and forming (CTFF) with the locus of initially situated along bridges between the envelopes of the major hysteresis curves. Concentric, oppositely directed magnetic moments coexist in the specimens when lies along the bridges. We focused on the cases where = 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 comparison of experimental and theoretical results shows that our simple model semi-quantitatively reproduces the major features of the observations on the specimen of Bi:2223/Ag tape.