Magnetic flux motion and its influence on transport properties of the high <i>T</i> <i>c</i> oxide superconductors

Abstract

High Tc superconductors exhibit significant flux motion due to a thermally activated creep process. The motion of the fluxoids dissipates energy. This dissipation causes a broadening of the resistive transition below Tc in a magnetic field as well as a logarithmic decay of the diamagnetic shielding moment in time. From the detailed structure of the broadened transition, empirical parameters are derived. The pinning strength is highly anisotropic, reflecting the anisotropy of the coherence length. Implications of an extraordinarily low activation energy are also addressed.