1Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, HungaryThe magnetic coupling between nanosize ferromagnetic bcc
crystalline grains embedded in a residual amorphous matrix was
studied by Fe-57 Mossbauer spectroscopy in nanocrystalline Fe-
Zr-B-Cu alloys studied above the Curie temperature of the
amorphous phase. It is shown that the ferromagnetic coupling is
mediated via an about two atomic layer thick interface region
between the: nanocrystallites.