Title :
Field effects on the dielectric property of YBCO bicrystal grain boundary junctions
Author :
Nakajima, K. ; Yokota, K. ; Myoren, H. ; Chen, J. ; Yamashita, T.
Author_Institution :
Res. Inst. of Electr. Commun., Tohoku Univ., Sendai, Japan
fDate :
6/1/1995 12:00:00 AM
Abstract :
Electric field effects on YBCO grain boundary Josephson junctions combined with inverted MIS (Metal, Insulator, Superconductor) structures were studied. Current steps and hysteresis recognized in current-voltage curves were strongly affected by the field. The current steps were attributed to the self-excited resonances, i.e., Fiske steps. Both the effects were interpreted by the field dependence of the effective dielectric constant of the grain boundary which has a certain contribution from the large dielectric constant of SrTiO/sub 3/ substrates. The effective dielectric constant normalized with barrier thickness of the junction was estimated to be about 40 nm/sup -1/ for the zero gate voltage and was decreased by a factor of 2 with the electric field of /spl plusmn/16 kV/cm. This feature is assumed adequate for tuning the phase velocity in the bicrystal grain boundaries.<>
Keywords :
Josephson effect; barium compounds; electric field effects; flux flow; grain boundaries; high-temperature superconductors; penetration depth (superconductivity); permittivity; superconducting device testing; yttrium compounds; Fiske steps; Josephson junctions; SrTiO/sub 3/; YBa/sub 2/Cu/sub 3/O/sub 7/-SrTiO/sub 3/; barrier thickness; bicrystal grain boundary junctions; current-voltage curves; dielectric property; effective dielectric constant; electric field effects; inverted MIS structures; phase velocity; self-excited resonances; zero gate voltage; Dielectric constant; Dielectric substrates; Dielectrics and electrical insulation; Grain boundaries; Hysteresis; Josephson junctions; Metal-insulator structures; Resonance; Voltage; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on