Scaling analysis of the static and dynamic critical exponents in under, over, and optimally-doped Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ films

TL;DR

This study investigates the critical behavior of Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ thin films across different doping levels, revealing mean-field behavior due to a small critical regime and a transition towards more conventional critical exponents as the transition width decreases.

Contribution

The paper provides the first detailed analysis of static and dynamic critical exponents in electron-doped cuprate thin films, highlighting their mean-field behavior and the influence of transition width on critical dynamics.

Findings

Critical regime size is approximately 25 mK, leading to mean-field behavior.

Static exponent ν is approximately 0.5 across all dopings.

Dynamic exponent z approaches 1.5 as transition width decreases.

Abstract

We report on current-voltage measurements of the zero-field normal-superconducting phase transition in thin films of Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ as a function of doping. We find that the small size of the critical regime in these materials ($\approx 25$ mK) gives rise to mean-field behavior at the phase transition with a static exponent of $\nu \approx 0.5$ for all dopings (in contrast to hole-doped $\mathrm{YBa_{2}Cu_{3}O_{7-\delta}}$). We also find mean-field behavior in the dynamic exponent $z$. This indicates that Pr$_{2-x}$Ce$_x$CuO$_{4-y}$ behaves similarly to conventional superconductors in contrast to other cuprate superconductors. However, as the transition width in our samples decreases, the dynamic critical exponent approaches $z=1.5$, similar to the critical exponent found in hole-doped $\mathrm{YBa_{2}Cu_{3}O_{7-\delta}}$.