Superconducting properties from AC susceptibility and harmonic generation in CuBa2Ca3Cu4Oy bulk superconductors

摘要

We measured for the first time the fundamental and higher harmonic components of AC susceptibility of CuBa2Ca3Cu4Oy superconductor produced by the high-pressure technique, in various experimental conditions (temperature, DC magnetic field, AC held amplitude and frequency). The results are discussed qualitatively in the frame of the critical state and other models in the literature. By using a very simple frequency-dependent critical state model, we estimated the parameters of practical interest, critical current density and pinning potential at various DC fields and temperatures and the irreversibility field. We also extrapolated our estimations to both practical temperature of 77 K and longer time scale as of DC magnetization and transport measurements. The results appeared to be quite self-consistent. (C) 2001 Published by Elsevier Science B.V. [References: 25]