Electric transport as a probe to unveil microscopic aspects of oxygen-depleted YBCO

TL;DR

This study uses electrical transport measurements to investigate how oxygen vacancies in YBCO influence conduction mechanisms, revealing trap states that correlate with oxygen deficiency and support impurity band models.

Contribution

It demonstrates that oxygen vacancies create potential wells affecting electrical conduction, modeled by Poole-Frenkel behavior, linking microscopic defect states to macroscopic transport properties.

Findings

Oxygen vacancies increase trap energy levels.

Electrical behavior fits Poole-Frenkel conduction model.

Trap energies correlate with oxygen deficiency.

Abstract

We report on the characterization of Pt-YBa$_2$Cu$_3$O$_{7-\delta}$ interfaces, focusing on how oxygen vacancies content ($\delta$) affects electrical transport mechanisms. Our study examines four Pt-YBa$_2$Cu$_3$O$_{7-\delta}$ samples with varying $\delta$ (0.12 $\leq \delta \leq$ 0.56) using voltage-current measurements across a temperature range. We successfully model the electrical behavior using a Poole-Frenkel conduction framework, revealing that oxygen vacancies create potential wells that trap carriers, directly influencing conduction. We observe that the energy of these traps increases as $\delta$ rises, in agreement with a peak previously detected in optical conductivity measurements. This result supports earlier interpretations, strengthening the proposed connection between oxygen vacancies and the ionization energy associated with impurity bands in YBa$_2$Cu$_3$O$_{7-\delta}$.