  We made electrical transport measurements along the c-axis of SmFeAsO0.85
single crystals, in both three- and four-terminal configurations, focusing on
examining the possible formation of Josephson coupling between FeAs
superconducting layers. Anisotropic bulk superconductivity was observed along
the c-axis, but without Josephson coupling, as confirmed by the absence of both
the hysteresis in current-voltage curves and the modulation of the critical
current by the in-plane magnetic fields. The variation of the critical currents
for different magnetic-field directions gives the anisotropy ratio of 5. This
three-dimensional electronic structure of our iron pnictide superconductors is
in clear contrast to the two-dimensional one observed in the cuprate
superconductors, another stacked superconducting system.
