Issue
EPL
Volume 86, Number 1, April 2009
Article Number 17005
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/86/17005
Published online 20 April 2009
EPL, 86 (2009) 17005
DOI: 10.1209/0295-5075/86/17005

Influence of the pseudogap on the Nernst coefficient of Y0.9 Ca0.1Ba2Cu3Oy

M. Matusiak1, 2, S. H. Naqib1, 3, I. Kokanović1, 4 and J. R. Cooper1

1   Cavendish Laboratory, Department of Physics, University of Cambridge J. J. Thomson Avenue, Cambridge CB3 0HE, UK, EU
2   Institute of Low Temperature and Structure Research, Polish Academy of Sciences P.O. Box 1410, 50-950 Wrocław, Poland, EU
3   Department of Physics, University of Rajshahi - Raj-6205, Bangladesh
4   Department of Physics, Faculty of Science, University of Zagreb - P.O. Box 331, Zagreb, Croatia

m.matusiak@int.pan.wroc.pl

received 23 December 2008; accepted in final form 15 March 2009; published April 2009
published online 20 April 2009

Abstract
We have studied the Nernst coefficient, $\nu (T)$, of epitaxial thin films of the superconductor Y1-xCaxBa2Cu3Oy with x = 0.05 and x = 0.1. The x = 0.1 sample has been measured at three different values of y, in the over- (OV), optimally- (OP), and under-doped (UD) states. As the doping level is reduced, $\nu (T)$ starts to fall linearly with T at the temperature (T*) where we expect to see the influence of the pseudogap. The onset temperature of the superconducting fluctuation contribution to $\nu (T)$ was found to vary slowly with the hole concentration (p) between p = 0.118 and 0.197. For the OP and UD samples, $\nu (T > T^{*})$ is unusually large, being comparable with $\vert S\,{\rm tan}\,\theta \vert$ where S is the Seebeck coefficient and $\theta $ the Hall angle.

PACS
74.25.Fy - Transport properties (electric and thermal conductivity, thermoelectric effects, etc.).
74.72.Bk - Y-based cuprates.
72.15.Jf - Thermoelectric and thermomagnetic effects.

© EPLA 2009