THE NATURE OF TRANSPORT CRITICAL CURRENT HYSTERESIS IN HTSC - MAGNETIC-FIELDS AND HIGH-PRESSURES

It was found that pressure has a strong influence on the critical current hysteresis loop of ceramics at H approximately 10 kOe. The phenomenon is attributed to the critical current hysteresis of separate Josephson contacts and is due to the Abrikosov vortex density gradient within granules. The gradient defines both the sign and the value of the pinning current, whereas the sign of Meissner reversible surface current component is determined by the external field H direction. As a result the critical current of Josephson contacts defined by the total surface value depends on the magnetic prehistory of a sample.