Vm. Krasnov et al., INFLUENCE OF THE 3D-2D CROSSOVER ON THE CRITICAL-CURRENT OF NB CU MULTILAYERS/, Physical review. B, Condensed matter, 50(2), 1994, pp. 1106-1110
We report the experimental observation of the Josephson critical curre
nt across layers, I(c) perpendicular-to, for Nb/Cu multilayers. Unique
samples with a small cross section (20 mum in diameter) consisting of
ten Nb/Cu junctions were fabricated for such measurements. A strong i
nfluence of the dimensional 3D-2D cross-over on the I(c)perpendicular-
to was observed. Thus, as the temperature becomes smaller than T2D, hy
steresis in the current-voltage characteristic appears and the behavio
r of the temperature dependence of the I(c)perpendicular-to changes. F
or T > T2D the diminishing of the hysteresis is caused by a sharp decr
ease of the junction capacitance in the 3D regime when the sample beco
mes uniform across layers. Calculation of the critical-current tempera
ture dependence I(c)perpendicular-to (T) for our multilayers was made.
An agreement between experimental and theoretical dependencies I(c)pe
rpendicular-to (T) was found. From the theoretical simulations, we hav
e obtained the dependence of the crossover and the critical temperatur
es of multilayers on the layer thicknesses, the boundary transparency,
and layer conductivity.