The experimental magnetic phase diagram for three characteristic Fe/Gd multilayered samples is confirmed on a microscopic scale by ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ Mössbauer spectroscopy using a special geometry. The iron moment rotation in the sample plane at a critical ${\mathit{H}}^{\mathrm{*}}$ external field is observed and signals the transition from an aligned to a twisted state. This behavior is accounted for within the framework of an improved mean-field model. Self-consistent spin maps are derived for given temperatures and external fields applied parallel to the sample plane. A unique set of exchange coupling constants is used to calculate both the mean magnetic properties and the Mössbauer spectroscopy data.

• Received 15 September 1993

DOI:https://doi.org/10.1103/PhysRevB.49.8815