Scaling analysis of the static and dynamic critical exponents in underdoped, overdoped, and optimally dopedPr2−xCexCuO4−yfilms

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 $\mathrm{YBa_{2}Cu_{3}O_{7-\delta}}$.