Vortex dynamics of (Bi,Pb)2Sr2Ca2Cu3Oy silver-sheathed tape by AC susceptibility measurements

Abstract

The complex ac susceptibility (χn=χ′ n- iχ′′ n) measurements were performed on a (Bi,Pb)2Sr2Ca2Cu3Oy silver-sheathed tape to study the vortex dynamics in a time window of 10-4-10-2s. The fundamental ac susceptibility of the tape as a function of temperature, ac field amplitudes and frequencies were obtained. The current dependent activation energy was derived as U(j)∝j-0.42, characteristic of the vortex glass/collective pinning model. By using such U(j) relation, higher harmonic susceptibilities χn (n=2-7) were obtained based on the numerical resolution of the flux diffusion equation. We found that theoretical results agree well with experimental data. © 2001 Elsevier Science B.V.