Variation of vortex structure characteristics of Bi-2223/Ag superconducting tapes with respect to applied magnetic field direction

Abstract

A study of the effects of external magnetic field orientation on the vortex characteristics was performed on a Bi-2223/Ag superconducting tape prepared by powder in tube method incorporating two-axial rolling and eccentric rolling processes. The data used for the analysis were obtained by magnetoresistance measurements in external magnetic field ranging from 0 to 16 T, at field orientations of 0°, 25°, 45°, 60°, and 90° with respect to the broad face of the tape. It is shown that the H irr and H TAFF phase boundaries tend to shift to lower temperature region with increasing field angle. On the other hand, the H FF curves remain roughly unaffected, leading to broadening of the unpinned liquid phase region between the H TAFF and H FF curves. Further analysis of the H irr( T) data for θ = 90° on the basis of Kim’s model of pancake depinning has yielded a whole set of vortex parameters and H c2 ( θ).