We have successfully fabricated a small thin stack with a small number
of intrinsic junctions on (Bi, Pb)(2)Sr2Ca2Cu3O10+x thin films. Mesa
structures with the junctions are fabricated on the surface of high-qu
ality films prepared by rf-sputtering and subsequent heat treatment. C
urrent-voltage (I-V) responses along the c-axis show large distinct hy
steresis, a clear multiple branching structure with a periodic voltage
jump and the edge structure, which represents the superconductive gap
. On reducing the number of the intrinsic stacked junctions, the estim
ated superconductive gap value increases. The thinnest stack exhibits
the I-V characteristic of a single junction. The value of the supercon
ductive gap estimated from the single junction sample is about 75 meV
at 4.2 K. The obtained I-V curve is explained quite well by assuming d
(x)2(-y)2 symmetry for the superconductive order parameter without the
term of gap suppression.