S-N transition of HIGH-Tc superconducting ring caused by induced current

The experimental investigation results of superconducting-normal state transitions in a high-T_c superconducting ring with induced current are presented. A transformer device is used, where the superconducting ring forms a secondary winding of a transformer. Using the analysis method based on an equivalent circuit of the transformer, the voltage and current in the ring vs time are obtained from oscilloscope traces of the voltage and current in the primary winding of the device. The dynamic voltage-current characteristic of the ring is found to have a hysteresis. This hysteresis is explained by the inertia of thermal processes and propagation of a resistive zone in the ring.