# Excess conduction of YBaCuO point contacts between 100 and 200 K

## TL;DR

This study investigates excess conductivity in YBaCuO-Ag point contacts between 100 and 200 K, revealing two-dimensional superconductivity above 120 K and suggesting an unknown phase with a critical temperature exceeding 200 K.

## Contribution

It provides new measurements of excess conductivity caused by fluctuational pairing in YBaCuO, indicating possible higher-temperature superconducting phases.

## Key findings

- Superconductivity above 120 K is two-dimensional.
- Excess conductivity is mainly due to electron fluctuations.
- Evidence suggests an unknown phase with $T'_c\gtrsim 200$ K.

## Abstract

$YBaCuO-Ag$ pressure point contacts with direct conduction are investigated. The excess (relative to the normal state) conductivity mainly caused by fluctuational pairing of electrons above $T_c$ is measured in the temperature interval 100-200~$K$. The superconductivity above 120~$K$ is found to be of the two-dimensional type. The obtained preliminary results indicate the presence of small amount of an unknown phase with $T'_c\gtrsim 200~K$ in $YBaCuO$.