This work is dedicated to the study of structural and magnetic properties of Mn films epitaxially grown on ͑001͒ bcc Fe. At room temperature, the Mn growth mode on ͑001͒ Fe is observed to be layer by layer, without any interdiffusion, as shown by reflection high-energy electron-diffraction and Auger spectroscopy. Moreover, Mn is observed to segregate on top of the Fe surface. Two-dimensional pure Mn films are thus grown and the structural and magnetic properties of these Mn films are investigated by in situ and ex situ x-ray absorption ͑EXAFS͒ and magnetic circular dichroism. For uncapped Mn films, a structural and magnetic transition is observed between 2 and 3 Mn monolayers. Up to 2 Mn atomic planes, the EXAFS oscillations are consistent with calculated EXAFS spectra assuming a bct structure close to the Fe bcc structure. A ferromagnetic behavior is observed in these films. From 3 to 10 atomic planes, the Mn film structure changes and the ferromagnetic behavior disappears. Moreover, EXAFS analysis shows that this structural transition occurs at higher thicknesses for Fe capped Mn films. Nevertheless, the ferromagnetic behavior observed on 0-2-MLthick uncapped Mn films is no more stable in thick bct Mn films capped by Fe.

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