Enhancement Of Critical Current Density Under Low Magnetic Fields Around 70 K In Bi_(2)Sr_(2)CaCu_(2)O_(y) Superconducting Whiskers

摘要

Electrical transport measurements for Bi_(2)Sr_(2)CaCu_(2)O_(y) whiskers with a single-step superconducting transition were carried out at high temperature ranging from 70 to 77 K below the superconducting transition temperature (velence 81.5-82.5 K) to investigate critical current density (J_(c)) under magnetic fields along the crystal c axis. The J_(c) parallel to the crystal a axis, which was estimated from the V-I curves, enhances under several ten oersteds, and then decreases with increasing the magnetic field. This peak effect in the low-field regime at high temperature has temperature dependence in contrast to the case of matching effects.