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We have studied the structure of epitaxial Mn sandwiches made of ∼ 1 monolayer (ML) Ag/3 ML Mn/Ag(100) by using photoemission methods and low-energy electron diffraction (LEED). Epitaxial films of 3 ML Mn grown on Ag(100) at room temperature (RT) are found to have a body-centered-tetragonal (bct) structure. Yet, upon deposition of ∼ 1 ML Ag, remarkable changes occur in the Mn film. X-ray photoelectron diffraction data reveal that the Mn layer relaxes towards a face-centered-cubic (fcc) structure with the lattice parameter of Ag. This implies an exceptionally large atomic volume for a 3d transition metal as well as unusual electronic and magnetic properties. Actually, an evolution towards more atomic-like behaviour is clearly evidenced by valence band and Mn3s core level photoemission data.

We have investigated the crystallographic structure of ultra-thin Mn films deposited at room temperature on a clean Ag(100) single crystal, using angle-resolved ultra-violet photoemission, X-ray photoelectron diffraction (XPD) and low-energy electron diffraction. The evolution of the Ag 4d valence band shows deviations from simple layer by layer growth. These results, combined with the XPD data, indicate that by ∼1–1.5 monolayers of Mn a two layers thick Mn-rich epitaxial MnAg alloy is formed that continues the face centered cubic lattice of the Ag substrate.