Low Frequency Noise in Superconducting Nanoconstriction Devices

Michal HATLE  Kazuaki KOJIMA  Katsuyoshi HAMASAKI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.8   pp.1169-1175
Publication Date: 1994/08/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Superconducting Devices)
Category: LTS
Keyword: 
superconducting weak link,  Andreev reflection,  SNS system,  low frequency noise,  conductance fluctuations,  

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Summary: 
The magnitude of low frequency noise is studied in a Nb-(nanoconstrictions)-NbN system with adjustable current-voltage characteristics. We find that the magnitude of low frequency noise decreases sharply with increasing the subgap conductivity of the device. We suggest a qualitative explanation of this observation in terms of gradual build up of the nanoconstriction region by field assisted growth. The decrease of low frequency noise is related to the "cleanliness" of the system as measured by the amount of Andreev reflection-related conductivity. The scaling of the magnitude of low frequency noise with device resistance is also discussed.