The effect of hydrostatic pressure on the normal and

The effect of hydrostatic pressure on the normal and superconducting states of Cadoped YBa2Cu3O7 single crystals
S. T. Jaeckel, V. N. Vieira, S. E. Nunes, L. F. Lopes, A. P. A. Mendonça, R. F. Lopes, D. L.
da Silva, L. Mendonça-Ferreira
Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, 96010-900,
Pelotas-RS, Brazil
P. Pureur, J. L. Pimentel Jr., F. M. Rosa
Instituto de Física, Universidade Federal do Rio Grande do Sul, P.O. Box 15051, 91501-970, Porto
Alegre-RS, Brazil
C. Adriano, P. G. Pagliuso
Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas - UNICAMP, P.O. Box
6165, Campinas-SP, Brazil
In this work we report the results of a study about the pressure effects on the normal and
superconducting properties of Ca doped YBa2Cu3O7. Single crystals of Y1-xCaxBa2Cu3O7
( x = 0, 0.01, 0.05, 0.10) were grown by the self-flux technique. Temperature dependent inplane resistivity measurements were carried out on a commercial Physical Properties
Measurement System. Hydrostatic pressure conditions (p < 15 kbar) were generated in a
Cu-Be piston-cylinder pressure cell. Our results indicate that substitution of Ca in the Y site
induces a reduction of Tc from 93 K for the undoped sample to 89.4 K for the x = 0.10
sample, while the application of pressure displaces the superconducting transition to higher
temperatures at a rate which is sample dependent. Similarly to the pure compound, the normal
state resistivity is reduced with increasing pressure. Features on the temperature derivative
curves and a preliminary analysis of the contribution of superconducting fluctuations to the
conductivity evidence the role of granularity effects on our Ca substituted samples. The
authors thank the financial support of CNPq, process # 478875/2008-8.