Measurements of the switching current distribution in REBa2Cu3Oy (RE = Eu, Er) intrinsic Josephson junctions

Abstract

We have investigated the switching dynamics of current biased REBa2Cu3Oy (RE123; RE = Eu, Er) intrinsic Josephson junctions (IJJs) with typical dimensions of ~1 × 1 × 0.1 μm3. The heavily under-doped Re123 IJJs exhibited clear multiple-branches with hysteresis structure. The critical current density, Jc, of both IJJs was 15 - 17 kA/cm2 at 4.2 K which was about ten times higher than that of Bi2Sr2CaCuOy (Bi2212) IJJs. From switching current measurements from the V = 0 state to the V ≠ 0 state of those IJJs, switching current distributions, P(I), were found to be significantly broader than that expected from the escape model of a single Josephson junction. This is in contrast with the fact that P(I) of Bi2212 IJJs have been well explained by the model. The P(I) of Eu123 IJJs were found to be independent of temperature below 1.4 K, which indicated the crossover temperature to the quantum regime from the thermally activated regime.