We present an atomistic model of interface alloying that presupposes exchange of adatoms with substrate atoms and floating of adatoms on the upper layers during deposition. Due to the existence of a preferred direction (the growth direction), the chemical profile near the interface proves to be asymmetrical. The floating algorithm combined with self-consistent calculations of atomic magnetic moments is used as a model for interpreting Mössbauer data obtained from 57 Fe-enriched interfacial tracer layers in Fe/Cr(001) superlattices. The superlattices were grown at different temperatures in order to modify their interface roughness. A linear correlation between calculated moment peaks and observed distinct magnetic hyperfine fields was found. Our experimental samples exhibit larger intermixing than the simplified theoretical model we used. The experimental giant magnetoresistance ratio was observed to increase with the decreasing fraction of certain 57 Fe atoms located in the interfacial region. Therefore, bulk scattering from impurity atoms appears to provide the main contribution to the giant magnetoresistance in Fe/Cr. Moreover, our theoretical results clarify the dependence of the short-wavelength period of interlayer coupling on the interface roughness in Fe/Cr.