Thin-film dc SQUID with low noise and drift

Publisher Website
Google Scholar
Abstract
We describe the fabrication and operation of thin‐film dc SQUID’s of cylindrical geometry that make use of shunted Nb‐NbOx‐Pb tunnel junctions. A typical noise power spectrum is shown. At frequencies between 2×10−2 Hz and the electronic roll‐off frequency, the flux resolution is 3.5×10−5 φ0/(Hz)1/2, corresponding to a magnetic field resolution of 10−10 G/(Hz)1/2. This resolution appears to be set by intrinsic sensor noise. Below 2×10−2 Hz, the spectrum is approximately 1/f. A 20‐h plot of SQUID output as a function of time demonstrates an average drift of less than 2×10−5 φ0/h.