Title :
The current-phase relation in high-T/sub c/ YBaCuO Josephson junctions
Author :
Ii´chev, E. ; Zakosarenko, V. ; Ijsselsteijn, R.R.J. ; Schultze, V. ; Meyer, H.-G. ; Heonig, H.E. ; Topfer, H.
Author_Institution :
Dept. of Cryoelectron., Inst. for Physical High Technol., Jena, Germany
fDate :
6/1/1999 12:00:00 AM
Abstract :
The current-phase relation (CPR) of YBa/sub 2/Cu/sub 3/O/sub 7-x/ step-edge as well as 36/spl deg/ and 45/spl deg/ grain boundary Josephson junctions (GB JJs) has been investigated experimentally in the temperature range between 4.2 K and 85 K. The junctions were incorporated into a washer-shaped superconducting ring with inductance L=80-300 pH. The ring was inductively coupled to a tank circuit with a resonance frequency between 9 and 40 MHz. The CPR has been obtained from the measurement of the impedance of the phase-biased junction. It is shown, that deviations from harmonic behavior of the apparent CPR for step-edge JJs can be explained by the influence of thermal noise. The CPR of 36/spl deg/ GB JJ were found to be very nearly sinusoidal in the measured temperature range. The CPR of 45/spl deg/ GB JJs were found to be nonsinusoidal at low temperatures. The reasons of this behavior are discussed.
Keywords :
Josephson effect; barium compounds; high-temperature superconductors; thermal noise; yttrium compounds; 4.2 to 85 K; 9 to 40 MHz; YBaCuO; current-phase relation; grain boundary Josephson junction; high-T/sub c/ superconductor; impedance; inductive coupling; resonance frequency; step-edge Josephson junction; tank circuit; thermal noise; washer-shaped superconducting ring; Coupling circuits; Grain boundaries; Impedance measurement; Inductance; Josephson junctions; RLC circuits; Resonance; Resonant frequency; Temperature distribution; Temperature measurement;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
