Andreev reflection at the normal-metal / heavy-fermion superconductor CeCoIn5 interface by point-contact spectroscopy

Wan Kyu Park, Laura Greene, John L. Sarrao, Joe D. Thompson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Dynamic conductance between a normal-metal (N) Au tip and the heavy-fermion superconductor (HFS) CeCoIn5 single crystal has been measured. The contact is shown to be in the Sharvin limit. Our clean conductance spectra are reproducibly obtained over a wide range of temperature (60 K to 400 mK). The background conductance shows a gradual development of asymmetry, starting at T* (∼ 45 K) down to Tc (2.3 K), which we attribute to the emergence of the heavy-fermion liquid. The enhanced sub-gap conductance observed below Tc, arising from Andreev reflection (AR), 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. From analyses using an extended Blonder-Tinkham-Klapwijk model, we find the conductance data at 400 mK is consistent with strong coupling (2Δ/kBT c = 4.64), and that the temperature dependence of the zero bias conductance is consistent with a d-wave order parameter, in agreement with the literature. However, attempts to fit full conductance curves as a function of temperature clearly show that this model cannot account for our data. We provide restrictions and suggestions for theoretical studies to account for AR at the N/HFS interface.

Original languageEnglish (US)
Title of host publicationLOW TEMPERATURE PHYSICS
Subtitle of host publication24th International Conference on Low Temperature Physics - LT24
Pages715-716
Number of pages2
DOIs
StatePublished - Dec 1 2006
EventLOW TEMPERATURE PHYSICS: 24th International Conference on Low Temperature Physics - LT24 - Orlando, FL, United States
Duration: Aug 10 2006Oct 17 2006

Publication series

NameAIP Conference Proceedings
Volume850
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherLOW TEMPERATURE PHYSICS: 24th International Conference on Low Temperature Physics - LT24
CountryUnited States
CityOrlando, FL
Period8/10/0610/17/06

Keywords

  • Andreev reflection
  • Blonder-Tinkham-Klapwijk model
  • Heavy-fermion superconductor
  • Point-contact spectroscopy

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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