Correlation between incoherent phase fluctuations and disorder in Y$_{1-x}$Pr$_x$Ba$_2$Cu$_3$O$_{7-\delta}$ epitaxial films from Nernst effect measurements

TL;DR

This study investigates the Nernst effect, resistivity, and Hall angle in Pr-doped YBCO films, revealing vortex-like excitations above T_c and correlating disorder with phase fluctuation regimes, advancing understanding of pseudogap phenomena.

Contribution

First measurements of the Nernst effect in Pr-YBCO films showing vortex-like excitations above T_c and establishing a link between disorder and phase fluctuation width.

Findings

Large Nernst signal observed above T_c

Correlation between disorder and phase fluctuation regime

Estimated T_c of ~110K for disorder-free YBCO

Abstract

Measurements of Nernst effect, resistivity and Hall angle on epitaxial films of Y$_{1-x}$Pr$_x$Ba$_2$Cu$_3$O$_{7-\delta}$(Pr-YBCO, 0$\leq x\leq$0.4) are reported over a broad range of temperature and magnetic field. While the Hall and resistivity data suggest a broad pseudogap regime in accordance with earlier results, these first measurements of the Nernst effect on Pr-YBCO show a large signal above the superconducting transition temperature(T$_c$). This effect is attributed to vortex-like excitations in the phase incoherent condensate existing above T$_c$. A correlation between disorder and the width of the phase fluctuation regime has been established for the YBCO family of cuprates, which suggests a T$_c\approx$110K for disorder-free YBa$_2$Cu$_3$O$_{7-\delta}$.