The domain structure of an antiferromagnetic superlattice is studied. Synchrotron Mössbauer and polarized neutron reflectometric maps show micrometer-size primary domain formation as the external field decreases from saturation to remanence. A secondary domain state consisting mainly of at least 1 order of magnitude larger domains is created when a small field along the layer magnetizations induces a bulk-spin-flop transition. The domain-size distribution is reproducibly dependent on the magnetic prehistory. The condition for domain coarsening is shown to be the equilibrium of the external field energy with the anisotropy energy.

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Structural and magnetic properties of Fe(5 nm)/Mn(t Mn )/Fe(5 nm) (t Mn from 0.5 to 3.0 nm͒ sandwich structures, grown by molecular-beam epitaxy between 50°C and 150°C, were investigated using reflection high-energy electron diffraction ͑RHEED͒, x-ray-diffraction, Mössbauer spectroscopy, and magnetization measurements. Epitaxial bct-Mn structures only form for t Mn Ͻ1 nm, independently of the growth temperature. Room-temperature conversion electron Mössbauer spectra are composed of two magnetic components with in-plane magnetic moments. The first subspectrum has hyperfine parameters close to ␣-Fe and is therefore associated with Fe atoms far from the interface regions. The second component, fitted with a hyperfine field ͑hf͒ distribution, has an isomer-shift value similar to ␣-Fe and a maximum in the distribution curve at about 31 T. This subspectrum is related to the Fe atoms close to the Mn layer ͑interface regions͒. Low-field components in the hf distribution curves indicate the presence of Fe atoms or/and Fe clusters in the Mn spacers. An Fe-Mn alloy was observed for the samples grown for temperatures higher than or equal to 50°C and where the RHEED patterns show the presence of the ␣-Mn phase. Magnetization data show that the Fe layers are ferromagnetically coupled for all trilayers prepared at substrate temperatures lower than 150°C. A noncollinear coupling was found for the trilayer with Mn thickness of 1 nm and grown at 150°C.

Epitaxially stabilized iron monosilicide films with the CsCl structure (B2-FeSi) have been investigated by conversion electron Mössbauer spectroscopy and x-ray diffraction. A detailed investigation of the elastic strain in these metastable layers is presented. Using hyperfine interaction information the tetragonal distortion of the silicide lattice could be quantified for layers as thin as 14Å. A general tendency for strain relaxation with increasing layer thickness is observed.

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