Abstract
It is known that sintered bulk samples of high Tc superconducting oxides have low critical current density and show hysteresis of critical currents in low magnetic fields. These phenomena are attributed to weak links at a grain boundary. In this work we report on the hysteresis of sintered bulk samples of high Tc superconducting oxides and of superconducting, relatively long bridges which have a constricted part made artificially. The former hysteresis is found to be very similar to the latter one. We consider that the hysteresis of sintered bulk samples of high Tc superconducting oxides occurs for the existence of superconducting, relatively long bridges and trapped flux in them.
