  This paper theoretically discusses the spin current in spin-triplet
superconductor / insulator / spin-triplet superconductor junctions. At low
temperatures, a midgap Andreev resonant state anomalously enhances not only the
charge current but also the spin current. The coupling between the Cooper pairs
and the electromagnetic fields leads to the Frounhofer pattern in the direct
current spin flow in magnetic fields and the alternative spin current under
applied bias-voltages.
