GROWTH, STRUCTURE, AND MAGNETIC-PROPERTIES OF THIN MN FILMS EPITAXIALLY GROWN ON (001) BCC FE

This work is dedicated to the study of structural and magnetic propert ies of Mn films epitaxially grown on (001) bcc Fe. At room temperature , the Mr, growth mode on (001) Fe is observed to be layer by layer, wi thout any interdiffusion, as shown by reflection high-energy electron- diffraction and Auger spectroscopy. Moreover, Mn is observed to segreg ate on top of the Fe surface. Two-dimensional pure Mn films are thus g rown and the structural and magnetic properties of these Mn films are investigated by in situ and ex situ x-ray absorption (EXAFS) and magne tic circular dichroism. For uncapped Mn films, a structural and magnet ic transition is observed between 2 and 3 Mn monolayers. Up to 2 Mn at omic planes, the EXAFS oscillations are consistent with calculated EXA FS spectra assuming a bet structure close to the Fe bcc structure. A f erromagnetic behavior is observed in these films. From 3 to 10 atomic planes, the Mn film structure changes and the ferromagnetic behavior d isappears. Moreover, EXAFS analysis shows that this structural transit ion occurs at higher thicknesses for Fe capped Mn films. Nevertheless, the ferromagnetic behavior observed on 0-2-ML-thick uncapped Mn films is no more stable in thick bet Mn films capped by Fe.