Correlation between incoherent phase fluctuations and disorder in Y 1−x Pr x Ba 2 Cu 3 O 7−δ 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−δ
(Pr-YBCO, 0
≤x≤
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
≈
110K for disorder-free YBa
2
Cu
3
O
7−δ
.