The effect of an exchange field on the electrical transport in thin films o
f metallic ferromagnetic manganites has been investigated. The exchange fie
ld was induced both by direct exchange coupling in a ferromagnet/antiferrom
agnet multilayer and by indirect exchange interaction in a ferromagnet/para
magnet metallic superlattice. The electrical resistance of the metallic man
ganite layers was found to be determined by the magnitude of the vector sum
of the effective exchange field and the external magnetic field.