Temperature Dependence of Critical Current Fluctuations in Nb/AlO\(\mathrm{_{x}}\)/Nb Josephson Junctions

We have measured the low frequency critical current noise in Nb/AlO\(_{\mathrm{x}}\)/Nb Josephson junctions. Unshunted junctions biased above the gap voltage and resistively shunted junctions biased near the critical current, \(I_{c}\), have been measured. For both, the spectral density of \(\delta...

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Bibliographic Details
Published in:arXiv.org 2008-12
Main Authors: Pottorf, Shawn, Patel, Vijay, Lukens, James E
Format: Article
Language:English
Subjects:
Critical current (superconductivity)
Josephson junctions
Temperature dependence
Variation
Online Access:Get full text
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Summary:We have measured the low frequency critical current noise in Nb/AlO\(_{\mathrm{x}}\)/Nb Josephson junctions. Unshunted junctions biased above the gap voltage and resistively shunted junctions biased near the critical current, \(I_{c}\), have been measured. For both, the spectral density of \(\delta I_{c}/I_{c}\), \(S_{i_{c}}(f)\), is proportional to \(1/f\), scales inversely as the area, \(A\), and is independent of \(J_{c} \equiv I_{c}/A\) over a factor of nearly 20 in \(J_{c}\). For all devices measured at 4.2 K, \(S_{i_{c}}\)(1 Hz)\(= 2.0 \pm 0.4 \cdot 10^{-12}\)/Hz when scaled to A=1 \(\mu\)m\(^{2}\). We find that, from 4.2 K to 0.46 K, \(S_{i_{c}}(f)\) decreases linearly with temperature.
ISSN:2331-8422
DOI:10.48550/arxiv.0809.3272