MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
by Andriy Moskalenko
B. Verkin Institute for Low Temperature Physics,
National Academy of Sciences of Ukraine,
Wednesday, May 23, 2001, 14.00 h
at IMM, Bldg. 305, Room 018, DTU
Abstract: Measurements of the superconducting gap in CeRu2 were performed by different methods and on samples of the different quality. Here we present a comparison of the behaviour of the superconducting gap in samples of different quality studied by point contacts. We propose a procedure for correction of the superconducting gap, D, taking into account pair-breaking effects, which result in almost equal gap values for both poly and single crystalline samples. The BCS-like behaviour of the gap in the temperature range below Tc* (Tc* Tc, where Tc is the critical temperature) is established indicating the presence of a gapless superconductivity region (between Tc* and Tc). The pair-breaking effect of paramagnetic impurities, supposedly Ce ions, is incorporated using the Scalsk i-Betbeder-Matibet-Weiss approach based on the Abrikosov-Gorkov theory. This all ows us to recalculate the superconducting order parameter Da in the presence of paramagnetic impurities and the gap DP in the pure case for polycrystalline CeRu2 samples and for single crystals. The value of 2DP(0) 187; 2 meV with 2DP(0)/kBTc » 3.75 is found in both cases indicating that CeRu2 is a moderately strong-coupled superconductor.