History effect of critical current density in superconducting multifilamentary Nb-Ti wire

摘要

DC magnetization and four-probe resistive measurements were carried out for Nb-Ti multifilamentary wires, and critical current densities in the filament and matrix were separated. The Campbell method was also used for measuring the effect of magnetic field history on critical current density in the matrix. The history dependence was found only for the current density induced in the matrix due to the proximity effect. This close correlation between the proximity effect and history effect shows a similarity to the phenomenon in high-T/sub c/ superconductors. The possible reason for the history effect in critical current density is discussed.