# Current - voltage characteristics of break junctions of high-$T_c$ superconductors

## TL;DR

This paper investigates the current-voltage characteristics of break junctions in various high-$T_c$ superconductors, revealing peculiarities of superconductor/normal-metal/superconductor junctions and modeling weak links with multiple Andreev reflections.

## Contribution

It introduces a model linking network of weak links to individual weak link behavior using the K"{u}mmel-Gunsenheimer-Nicolsky approach.

## Key findings

- Experimental I-V curves show superconductor/normal-metal/superconductor junction features.
- The model successfully describes the I-V characteristics of weak links.
- Multiple Andreev reflections are significant in the behavior of these junctions.

## Abstract

The current-voltage ($I$-$V$) characteristics of break junctions of polycrystalline La$_{1.85}$Sr$_{0.15}$CuO$_4$, Y$_{0.75}$Lu$_{0.25}$Ba$_2$Cu$_3$O$_{7-\delta}$, Bi$_{1.8}$Pb$_{0.3}$Sr$_{1.9}$Ca$_2$Cu$_3$O$_x$ and composite YBa$_2$Cu$_3$O$_{7-\delta}$ + Ag are investigated. The experimental $I$-$V$ curves exhibit the specific peculiarities of superconductor/normal-metal/superconductor junctions. The relation between an $I$-$V$ characteristic of network of weak links and $I$-$V$ dependencies of typical weak links is suggested to describe the experimental data. The $I$-$V$ curves of typical weak links are calculated by the K\"{u}mmel - Gunsenheimer - Nicolsky model considering the multiple Andreev reflections.