Comparison between conventional flux creep in constant magnetic field and the effect of creep on the shape of magnetic hysteresis loops in high-Tc superconductors

Abstract

The effect of the magnetic induction sweep rate B= delta Bext/ delta t on the shape of magnetic hysteresis loops, in particular on the induced magnetic moment m ( implies/implied by critical current jc) was calculated directly from the basic mechanism of thermally activated flux creep introduced by Anderson taking jc constant through the sample. It was found (a) that m changes linearly with ln mod B mod , and (b) that delta m/ delta ln mod B mod is equal to - delta m/ delta ln t in conventional relaxation at Bext=constant. Similar results were obtained recently from a phenomenological model using differential susceptibility chi to characterize the effect of sweeping Bext.