Andreev reflection at the normal-metal/heavy-fermion superconductor CeCo In5 interface

W. K. Park, Laura Greene, J. L. Sarrao, J. D. Thompson

Research output: Contribution to journalArticle

Abstract

The dynamic conductance across nanoscale junctions consisting of a normal-metal (N) and a heavy-fermion superconductor (HFS) is measured over a wide temperature range (60 K to 400 mK). The N/HFS (AuCeCo In5) contact is shown to be in the Sharvin limit. The background conductance develops a gradual asymmetry with decreasing temperature starting at the heavy-fermion liquid coherence temperature, T* ∼45 K, to the onset of superconducting coherence, Tc =2.3 K. The enhanced subgap conductance observed below Tc arises from Andreev reflection. This enhancement is an order of magnitude smaller (∼13.3% at 400 mK) than that observed for N/conventional superconductors but consistent with other N/HFS data reported. Attempts to fit to the full conductance curve as a function of temperature with extended Blonder-Tinkham-Klapwijk models, including those that account for the breakdown of the Andreev approximation and renormalizations of the Fermi momenta, clearly show that existing models cannot account for our data. We provide a theoretical framework for understanding the N/HFS Andreev conversion process.

Original languageEnglish (US)
Article number052509
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume72
Issue number5
DOIs
StatePublished - Aug 1 2005

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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