Abnormal Transverse-Field Effects in Nonideal Type 2 Superconductors. II. Influence of Dimension Ratios in a Superconducting Ribbon

In a nonideal superconducting wire, a number of strange magnetic phenomena have been observed in an AC magnetic field superposed perpendicularly on a DC bias field. When the DC bias field is applied parallel to the wire axis, these strange phenomena are called longitudinal-field effects, while abnonnal transverse-field effects are observed when the DC bias field is perpendicular to the wire axis. In this paper, the conditions for the appearance of the abnormal transverse-field effect are investigated in detail for a superconducting Nb50%Ta ribbon. When the dimension ratios were changed, we observed a change in the magnetic behavior from the longitudinal-field to the abnormal transverse-field effect. It is suggested that such a change originates from a change in the pinning characteristics due to various motional styles of flux lines.