Coexistence of the hot-spot effect and flux-flow instability in high-Tc superconducting films

Voltage jumps were observed in current-voltage (I-V) characteristics of YBa2Cu37-delta superconducting film. The measurements demonstrate that the observed voltage instability originates from two different mechanisms, depending on the temperature and the magnetic field. This is inferred from the shape of the I-V characteristics, the temperature and magnetic-field dependencies of the critical current, and the critical voltage associated to the voltage jumps. Relevant models indicate that the voltage jumps at low temperatures are due to the hot-spot effect, whereas those at temperatures near T-c are due to flux-flow instabilities. [SO163-1829(98)01741-X].