Switching current distributions and subgap structures of underdoped (Hg,Re)Ba2Ca2Cu3O8+d intrinsic Josephson junctions

TL;DR

This study explores the switching current distributions and subgap structures in underdoped (Hg,Re)Ba2Ca2Cu3O8+d intrinsic Josephson junctions, revealing high plasma frequency and a crossover from thermal to quantum escape mechanisms.

Contribution

It provides the first detailed analysis of switching current distributions and subgap features in (Hg,Re)1223 IJJs, highlighting their high plasma frequency and quantum tunneling behavior.

Findings

Switching current distributions match thermal escape model above 5 K.

Plasma frequency estimated at 1.3 THz, among the highest for cuprates.

Observation of crossover from thermal activation to quantum tunneling below 5 K.

Abstract

We have investigated the intrinsic Josephson properties in slightly underdoped (Hg,Re)Ba2Ca2Cu3Oy [Hg(Re)1223] intrinsic Josephson junctions (IJJs) with a dimension of 1.0x1.5x0.11 um^3. The current-voltage characteristics of the IJJs exhibit clear multiple branches with subgap structures similar to those of other cuprate superconductors. The switching current distributions P(I) from the zero-voltage to the nonzero-voltage state in the current-biased IJJs agree well with the theoretical curves of the thermally assisted escape model at temperatures above ~5 K. The plasma frequency fp of the IJJs is estimated to be 1.3 THz from the fluctuation-free critical current density of 2.0x10^5 A/cm2, which is one of the highest among cuprate superconductors, reflecting the high Tc and a relatively low anisotropy of the Re doped Hg system. The P(I) gradually becomes independent of temperature below ~5 K, which suggests a crossover of the escape process from thermal activation to quantum tunneling at such a high temperature.