Title :
DC-SQUIDs with low noise and large beta /sub L/-values on (Y)ZrO/sub 2/ bicrystal substrate
Author :
Olsson, H.K. ; Koch, R.H. ; Nilsson, P.-A. ; Stepantsov, E.A.
Author_Institution :
Dept. of Phys., Chalmers Univ. of Technol., Goteborg, Sweden
fDate :
3/1/1993 12:00:00 AM
Abstract :
High-quality YBa/sub 2/Cu/sub 3/O/sub 7/ DC-SQUIDs (superconducting quantum interference devices) fabricated on bicrystal (Y)ZrO/sub 2/ substrates have been operated at temperatures from 10 K to the critical temperature at 89 K. Stable operation with low white noise levels is found even for beta /sub L/-values as large as 60 for these nonhysteretic junctions ( beta /sub c/<<1). In addition, two noise sources were identified in the 1/f noise: (1) a junction critical current dependent noise S/sub v/ approximately I/sub 0/(T)/sup 2.7/ and (2) a narrow peak in S/sub v/(T) centered at 87 K with its origin in vortex motion within the superconductor. Optimum low-noise operation was obtained in a minimum at 85 K with a flux noise S/sub Phi /(10 Hz)=1.5*10/sup -9/ Phi /sub 0//sup 2//Hz.<>
Keywords :
Josephson effect; SQUIDs; barium compounds; electron device noise; high-temperature superconductors; white noise; yttrium compounds; 1/f noise; 10 to 89 K; DC-SQUIDs; YBa/sub 2/Cu/sub 3/O/sub 7/; bicrystal ZrO/sub 2/ substrate; critical temperature; flux noise; junction critical current dependent noise; low white noise levels; noise sources; nonhysteretic junctions; optimum low noise operation; superconducting quantum interference devices; voltage noise; vortex motion; Circuit noise; Critical current; Josephson junctions; Noise level; Noise measurement; SQUIDs; Superconducting device noise; Surface resistance; Temperature; Transfer functions;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
