Anisotropic AC behavior of multifilamentary Bi-2223/Ag tapes

In this communication, we report on the anisotropy of the superconducting properties of multifilamentary Bi-based tapes experimentally investigated by AC magnetic susceptibility measurements. The susceptibility χ=χ´-jχ´´ was measured using a commercial system and a couple of orthogonal pick-up coils. The χ´´ vs. temperature curves were shown to exhibit two peaks. The smaller of the peaks, occurring near T=72 K, was only visible for particular field directions and within a given frequency window. Such results point out the role played by the phase difference between the applied magnetic field and the internal magnetic field seen by the filaments.