Title :
Step-edge Josephson junctions and their use in HTS single-layer gradiometers
Author :
Millar, A.J. ; Romans, E.J. ; Carr, C. ; Eulenburg, A. ; Donaldson, G.B. ; Pegrum, C.M.
Author_Institution :
Dept. of Phys. & Appl. Phys., Strathclyde Univ., Glasgow, UK
fDate :
3/1/2001 12:00:00 AM
Abstract :
We describe reproducible technology for fabricating YBa2Cu3O7 step edge Josephson junctions on SrTiO3 substrates. We report on the electrical characteristics of the junctions at 77 K and the dependence on the ratio of film thickness to step height. Single-layer gradiometers incorporating step-edge junction dc SQUIDs have been fabricated. We compare the performance of identical SQUID gradiometers based on our step-edge junctions and on 24° SrTiO3 bicrystal junctions. Gradiometric SQUIDs (G-SQUIDs) incorporating step-edges have also been fabricated. We measured the effective area of several G-SQUIDs to be in the range of 1-2 μm2, approximately two orders of magnitude lower than for conventional SQUIDs of similar inductance. We demonstrate that when incorporated into a gradiometer the G-SQUID leads to an improved performance in an unshielded environment
Keywords :
Josephson effect; SQUID magnetometers; barium compounds; critical currents; high-temperature superconductors; inductance; superconducting device noise; yttrium compounds; 24° SrTiO3 bicrystal junctions; 77 K; HTS single-layer gradiometers; SQUID gradiometers; SrTiO3; SrTiO3 substrates; YBa2Cu3O7; YBa2Cu3O7 step edge Josephson junctions; electrical characteristics; film thickness; gradiometric SQUIDs; inductance; reproducible technology; step height; step-edge junction dc SQUIDs; unshielded environment; Electric variables; Fabrication; Grain boundaries; High temperature superconductors; Josephson junctions; Magnetic fields; Physics; SQUIDs; Substrates; Transistors;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
