Iv. Roshchin et al., ANOMALOUS BEHAVIOR OF THE CRITICAL-CURRENT OF A GRAIN-BOUNDARY JOSEPHSON-JUNCTION IN A BULK (BA,K)BIO3 BICRYSTAL, JETP letters, 59(3), 1994, pp. 168-172
The electrical transport properties of grain boundaries in bulk bicrys
tals of the oxide superconductor Ba0.55K0.45BiO3 have been studied. Th
e grain boundary in these bicrystals is a Josephson barrier. Near the
transition temperature, the critical current of this barrier has a pow
er-law temperature dependence with a critical exponent of 3/2. The cri
tical current of a grain boundary exhibits a nonmonotonic behavior as
the temperature is lowered. A possible interpretation of this behavior
is discussed.