Title :
Critical current behavior of Ag-coated YBa2Cu3O7-x thin films
Author :
Ono, R.H. ; Beall, J.A. ; Harvey, T.E. ; Reintsema, C.D. ; Johansson, M. ; Cromar, M.W. ; Goodrich, L.F. ; Moreland, J. ; Roshko, A. ; Stauffer, T.C.
Author_Institution :
Nat. Inst. of Stand. & Technol., Boulder, CO, USA
fDate :
3/1/1991 12:00:00 AM
Abstract :
The authors studied the behavior of high-quality Ba2Cu 3O7-x (YBCO) thin films with Ag overlayers. The authors chose to study Ag in detail because of its widespread use as contact metallization and because of their earlier studies of proximity effects in YBCO. The details of transport critical current measurements are presented. It is shown that the Ag coatings can reduce normal state resistance while not degrading the critical current density. The key technological result is that the various thicknesses of Ag that were used did not reduce Jc or Jc(H). Critical current densities in excess of 106 A/cm2 have been achieved at temperatures greater than 76 K. An unusual effect was seen in Jc(H) when the field was oriented perpendicular to the c axis of the film. The Jc at 1 T was higher in samples with 10-nm coatings of Ag than in similar uncoated samples. It was also shown that the composite resistance of Ag-YBCO bilayers can be much lower than the resistance of uncoated YBCO
Keywords :
barium compounds; composite superconductors; critical current density (superconductivity); high-temperature superconductors; proximity effect; silver; superconducting thin films; yttrium compounds; Ag overlayers; YBa2Cu3O7-x-Ag; contact metallization; critical current density; high temperature superconductor; normal state resistance; proximity effects; thin films; transport critical current measurements; Coatings; Critical current; Critical current density; Current measurement; Degradation; Electrical resistance measurement; Metallization; Proximity effect; Transistors; Yttrium barium copper oxide;
Journal_Title :
Magnetics, IEEE Transactions on
