Switching Dynamics of Bi_2Sr_2CaCu_2O_<8+δ> Intrinsic Josephson Junctions : Macroscopic Quantum Tunneling and Self-Heating Effect(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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The switching dynamics of current-biased Bi_2Sr_2CaCu_2O_<8+δ> intrinsic Josephson junctions (IJJs) was studied to clarify the effects of d-wave superconductivity and the stack structure on switching properties. High-quality IJJs were fabricated, and then the temperature dependence of the switching probability distribution was measured for the first and second switchings. Although the standard deviation of the distribution detected for both switchings showed similar saturation characteristics with decreasing temperature, the temperature at saturation was about thirteenfold higher for the second switching than for the first switching. The properties of the first switching can be explained in terms of a conventional underdamped JJ, that is, macroscopic quantum tunneling below the crossover temperature, and thermal activation with a quality factor of 70±20 above the crossover temperature. In contrast, the relatively higher effective temperature for the second switching evaluated from the switching probability distribution suggests a predominant thermal activation process under the influence of the self-heating effect even at sufficiently low temperatures.
2008-10-15