Switching Dynamics of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ Intrinsic Josephson junctions: Macroscopic Quantum Tunneling and Self-Heating Effect

摘要

The switching dynamics of current-biasedBi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ intrinsic Josephson junctions (IJJs)was studied to clarify the effect of d-wave superconductivity and the stackstructure on the switching properties. High quality IJJs were fabricated, andthen the temperature dependence of the switching probability distribution wasmeasured for the first and second switchings. Although the standard deviationof the distribution detected for both switchings showed similar saturationcharacteristics with decreasing temperature, the temperature at saturation wasabout 13 times higher for the second switching than for the first switching.The properties of the first switching can be explained in terms of aconventional underdamped JJ, that is, macroscopic quantum tunneling below thecrossover temperature, and thermal activation with quality factor of 70$\pm$20above the crossover temperature. In contrast, the relatively higher effectivetemperature for the second switching evaluated from the switching probabilitydistribution suggests a dominant thermal activation process under the influenceof the self-heating effect even at sufficiently low temperature.