Magnetic relaxation in single-crystal Tl2Ca1Ba 2Cu2O8 superconductors is reported. Typical logarithmic flux creep has been observed at low temperatures. At high temperatures and fields, different flux dynamics are observed: first, nonlogarithmic dependence followed by the appearance of reverse creep, i.e., increasingly negative magnetization. This latter effect begins after a temperature- and field-dependent wait time. To explain reverse creep flux-line roughening, driven by pinning randomness, is considered.
ASJC Scopus subject areas
- Physics and Astronomy(all)