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

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 $\le \delta \le$ 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${}_{7-\delta }$.