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

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$\le x\le$0.4) are reported over a broad range of temperature and magnetic field. While the Hall and resistivity data suggest a broad pseudogap regime in accordance with earlier results, these first measurements of the Nernst effect on Pr-YBCO show a large signal above the superconducting transition temperature(T${}_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 }$.

5 pages, 6 figures

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