Switching Current Measurements of EuBa2Cu3Oy Intrinsic Josephson Junctions

TL;DR

This study examines the switching dynamics of EuBa2Cu3Oy intrinsic Josephson junctions with different anisotropy parameters, revealing deviations from classical models and evidence of macroscopic quantum tunneling at very low temperatures.

Contribution

It provides new insights into the switching behavior of Eu123 IJJs, highlighting their strongly-coupled nature and quantum effects at low temperatures, unlike previously studied weakly-coupled IJJs.

Findings

Deviations from thermally activated escape model observed.

Switching current distributions are temperature-independent below certain low temperatures.

Evidence of macroscopic quantum tunneling at liquid helium temperatures.

Abstract

We investigated the switching dynamics of two kinds of EuBa2Cu3Oy (Eu123) intrinsic Josephson junctions (IJJs) with different anisotropy parameters gamma (= (m*c/m*ab)1/2) tuned to 37 and 22. In contrast to weakly-coupled IJJs in Bi2212, significant deviations from the thermally activated escape model of a single-stack Josephson junction were observed in their switching current distributions, P(I), due to the strongly-coupled nature of the Eu123 IJJs, The P(I) of the two IJJs are found to be independent of temperature, below 1.4 K and 4.2 K, respectively; which indicates the observation of macroscopic quantum tunneling at high temperatures of liquid He.