A1 Refereed original research article in a scientific journal
Andreev-reflection spectroscopy with superconducting indium-A case study
Authors: Gloos K, Tuuli E
Publisher: AMER INST PHYSICS
Publication year: 2013
Journal: Low Temperature Physics
Journal name in source: LOW TEMPERATURE PHYSICS
Journal acronym: LOW TEMP PHYS+
Number in series: 3
Volume: 39
Issue: 3
First page : 252
Last page: 258
Number of pages: 7
ISSN: 1063-777X
DOI: https://doi.org/10.1063/1.4794999
Abstract
We have investigated Andreev reflection at interfaces between superconducting indium (T-c = 3.4 K) and several normal conducting nonmagnetic metals (palladium, platinum, and silver) down to T = 0.1K as well as zinc (T-c = 0.87 K) in its normal state at T = 2.5 K. We analyzed the point-contact spectra with the modified one-dimensional BTK theory valid for ballistic transport. It includes Dynes' quasiparticle lifetime as fitting parameter C in addition to superconducting energy gap 2 Delta and strength Z of the interface barrier. For contact areas from less than 1 nm(2) to 10 000 nm(2) the BTK Z-parameter was close to 0.5, corresponding to transmission coefficients of about 80%, independent of the normal metal. The very small variation of Z indicates that the interfaces have a negligible dielectric tunneling barrier. Also Fermi surface mismatch does not account for the observed Z. The extracted value Z approximate to 0.5 can be explained by assuming that practically all of our point contacts are in the diffusive regime. (C) 2013 American Institute of Physics. [ http://dx.doi.org/10.1063/1.4794999]
We have investigated Andreev reflection at interfaces between superconducting indium (T-c = 3.4 K) and several normal conducting nonmagnetic metals (palladium, platinum, and silver) down to T = 0.1K as well as zinc (T-c = 0.87 K) in its normal state at T = 2.5 K. We analyzed the point-contact spectra with the modified one-dimensional BTK theory valid for ballistic transport. It includes Dynes' quasiparticle lifetime as fitting parameter C in addition to superconducting energy gap 2 Delta and strength Z of the interface barrier. For contact areas from less than 1 nm(2) to 10 000 nm(2) the BTK Z-parameter was close to 0.5, corresponding to transmission coefficients of about 80%, independent of the normal metal. The very small variation of Z indicates that the interfaces have a negligible dielectric tunneling barrier. Also Fermi surface mismatch does not account for the observed Z. The extracted value Z approximate to 0.5 can be explained by assuming that practically all of our point contacts are in the diffusive regime. (C) 2013 American Institute of Physics. [ http://dx.doi.org/10.1063/1.4794999]
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