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Point-Contact Spectroscopy of the Heavy-Fermion Superconductor CeCoIn$_5$

W. K. Park·L. H. Greene·J. L. Sarrao·J. D. Thompson
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Abstract

The dynamic conductance of the heavy-fermion superconductor CeCoIn$_5$ is measured by point-contact spectroscopy as a function of temperature from 60 K down to 400 mK. The contact between the gold tip and the single-crystal is shown to be in the Sharvin limit with the enhanced sub-gap conductance arising from Andreev reflection. The zero-bias conductance data are best fit using the extended Blonder-Tinkham-Klapwijk model with a d-wave superconducting order parameter. A fit to the full conductance curve at 400 mK indicates strong coupling ($2Δ(0)/k_\textrm{B}T_\textrm{c} = 4.6$) and quantifies the suppressed Andreev reflection signal, which is a signature of normal-metal/heavy-fermion superconductor junctions. Possibilites for theoretical modeling to account for the suppressed Andreev conductance are suggested.

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W. K. Park, L. H. Greene, J. L. Sarrao, J. D. Thompson. 2004-11-16. Point-Contact Spectroscopy of the Heavy-Fermion Superconductor CeCoIn$_5$. https://doi.org/10.1103/physrevb.72.052509

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