Influence of viscous flux flow on AC magnetisation of high-Tc superconductors

Abstract

Using the parameters of high-Tc superconductors, the role of the flux flow in AC magnetic fields is expected to be much more pronounced than in classical type II superconductors. Therefore, the authors calculated the influence of the viscous flow of vortices on the magnetic field distribution and the hysteresis losses. The derived dependence on magnetic field and frequency of the AC susceptibility and losses is compared with experimental results. Although the results agree qualitatively with the experiments, the differences in magnitude indicate that the flux-flow effects in high-Tc superconductors are much less evident that was supposed by some theoretical considerations. The authors discuss some reasons for the discrepancies.