Title :
YBCO DC SQUIDs utilizing sapphire step edge junctions
Author :
Berezin, A.B. ; Yuan, C.W. ; de Lozanne, A.L.
Author_Institution :
Dept. of Phys., Texas Univ., Austin, TX, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
A number of superconducting quantum interference devices (SQUIDs) which utilize a step edge grain-boundary junction process on sapphire substrates have been measured. White noise levels of about 7 mu Phi /sub 0// square root Hz at 1 Hz in a 16-pH device at 77 K were measured. By modulating the bias current, only about a factor of 3 to 4 reduction in the amplitude of low-frequency noise is achieved. Excess flux noise is believed to constitute the remainder. A square washer configuration yields flux noise at 100 Hz at about 140 mu Phi /sub 0// square root Hz, giving a field sensitivity of 11 pT/ square root Hz. Measured hysteresis is about -1 to -5*10/sup -3/ in a low ambient field.<>
Keywords :
SQUIDs; barium compounds; electron device noise; grain boundaries; high-temperature superconductors; sapphire; white noise; yttrium compounds; 77 K; Al/sub 2/O/sub 3/; DC SQUIDs; YBa/sub 2/Cu/sub 3/O/sub 7/-Al/sub 2/O/sub 3/; flux noise; grain-boundary junction process; low-frequency noise; sapphire step edge junctions; sapphire substrates; square washer configuration; superconducting quantum interference devices; white noise levels; Amplitude modulation; Interference; Josephson junctions; Low-frequency noise; Noise measurement; SQUIDs; Superconducting device noise; Superconducting devices; White noise; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
