Scaling of the transport properties in theY1−yPryBa2Cu3Oxsystem

Abstract

We report on the temperature dependent resistivity of ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ and $({\mathrm{Y}}_{0.6}{\mathrm{Pr}}_{0.4}{)\mathrm{B}\mathrm{a}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ epitaxial thin films, measured in pulsed magnetic fields up to 50 T. The zero-field $\ensuremath{\rho}(T)$ data for various levels of hole doping p can be scaled onto one single universal curve by using a linear transformation of both temperature and resistivity. This universal curve exhibits a linear $\ensuremath{\rho}(T)$ at high temperatures $Tg{T}^{*}$ (region I) and a superlinear $\ensuremath{\rho}(T)$ at intermediate temperatures ${T}_{\mathrm{MI}}lTl{T}^{*}$ (region II). The ground state in the low temperature region $Tl{T}_{\mathrm{MI}}$ (region III) is masked by the presence of superconductivity below ${T}_{c},$ but is accessible in high magnetic fields. The high field measurements reveal that ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ (for $xl6.8)$ and $({\mathrm{Y}}_{0.6}{\mathrm{Pr}}_{0.4}{)\mathrm{B}\mathrm{a}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{x}$ (for all levels of oxygen content) have an ``insulatinglike'' ground state at low temperatures and that the universal scaling may be extended to region III. The existence of a universal $\ensuremath{\rho}(T)$ curve indicates that the same mechanisms are dominating the scattering of the charge carriers in these materials but with a different energy scale depending on the carrier concentration and/or the defect structure.