Title :
Low excess flux noise in YBa/sub 2/Cu/sub 3/O/sub 7-x/ dc SQUIDs cooled in static magnetic fields
Author :
Dantsker, E. ; Tanaka, S. ; Nilsson, P.A. ; Kleiner, R. ; Clarke, J.
Author_Institution :
Dept. of Phys., California Univ., Berkeley, CA, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
We have investigated the effect of device geometry on the excess low frequency 1/f noise of thin-film YBCO dc SQUIDs cooled in static magnetic fields. The key factor in eliminating this noise is the reduction of the linewidth of the SQUID loop to a value below the average separation of the flux vortices. The spectral density of the flux noise in these devices was independent of cooling field up to 33 /spl mu/T in the best case. Estimates indicate that incorporating this device into a directly-coupled magnetometer would not increase the noise further.
Keywords :
1/f noise; SQUID magnetometers; barium compounds; flux flow; high-temperature superconductors; magnetic fields; superconducting device noise; superconducting thin films; yttrium compounds; 0 to 33 muT; 1/f noise; SQUID loop; YBa/sub 2/Cu/sub 3/O/sub 7/; cooling field; dc SQUIDs; device geometry; directly-coupled magnetometer; excess flux noise; flux vortices; linewidth reduction; spectral density; static magnetic fields; Cooling; Frequency; Geometry; Low-frequency noise; Magnetic films; Magnetic noise; Noise reduction; SQUIDs; Thin film devices; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
