Title :
Misorientation dependence of DC SQUID of YBa2Cu3O7-X grain boundary junctions on MgO bicrystal substrates
Author :
Huang, Tung-Wuu ; Niu, Dow-Chieh
Author_Institution :
Chung-Shan Inst. of Sci. & Technol., Tao-Yuan, Taiwan
fDate :
6/1/2005 12:00:00 AM
Abstract :
Thermal diffusion-bonded bicrystals of MgO with the configuration of [00l] tilt boundaries were incorporated as substrates to create artificial grain boundaries of epitaxial YBa2Cu3O7-X (YBCO) thin films. The transport properties of the YBCO grain boundary junctions across various misorientation angles Θ, Θ=10°, 20°, 30°, 40°, have been studied. The critical current density across the grain boundaries decreased exponentially as the misoriented angle increasing. The current-voltage characteristics of the Θ=10°, 20° grain boundary junctions typically exhibited flux-flow or flux-creep like behavior; and the Θ=30°, 40° grain boundary junctions revealed a resistive shunted junction (RSJ) like I-V characteristics. The transition from strong coupling for low angle grain boundary to weak-link behavior occurred with Θ>20°. The dc SQUIDs made of θ=30° and 40° misoriented grain boundary showed periodic modulation of voltage-flux characteristics up to 77 K, IcRn = 0.4 mV, with ΔV=6 μV.
Keywords :
SQUIDs; barium compounds; bicrystals; critical current density (superconductivity); flux creep; flux flow; grain boundaries; high-temperature superconductors; magnesium compounds; superconducting epitaxial layers; yttrium compounds; Josephson devices fabrication; Josephson junctions; YBa2Cu3O7-x; [001] tilt boundary; artificial grain boundary; bicrystal substrates; critical current density; current-voltage characteristics; dc SQUID; epitaxial thin films; flux creep; flux flow; grain boundary junctions; misorientation dependence; resistive shunted junction; thermal diffusion bonded bicrystals; transport property; Critical current density; Fabrication; Grain boundaries; High temperature superconductors; Josephson junctions; SQUIDs; Substrates; Superconducting devices; Superconducting films; Yttrium barium copper oxide; Josephson devices fabrication; Josephson junctions; SQUIDs; superconducting devices;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2005.849739