Wilson ratio in Yb-substituted CeCoIn5
Department of Physics and Astronomy, University of California Irvine - Irvine, CA 92697-4575, USA
2 Department of Condensed Matter Physics, University of Geneva - 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
3 Département de Physique, Université de Montréal - Montréal H3C 3J7, Canada
Accepted: 29 October 2010
We have investigated the effect of Yb substitution on the Pauli-limited, heavy-fermion superconductor, CeCoIn5. Yb acts as a non-magnetic divalent substituent for Ce throughout the entire doping range, equivalent to hole doping on the rare-earth site. We found that the upper critical field in (Ce,Yb)CoIn5 is Pauli limited, yet the reduced (H,T) phase diagram is insensitive to disorder, as expected in the purely orbitally limited case. We use the Pauli-limiting field, the superconducting condensation energy and the electronic specific-heat coefficient to determine the Wilson ratio (RW), the ratio of the specific-heat coefficient to the Pauli susceptibility in CeCoIn5. The method is applicable to any Pauli-limited superconductor in the clean limit.
PACS: 74.25.Dw – Superconductivity phase diagrams / 74.70.Tx – Heavy-fermion superconductors / 74.62.Dh – Effects of crystal defects, doping and substitution
© EPLA, 2010