Abstract:
The magnetism of epitaxial fcc-Fe films deposited on Cu(100) and Co(100), and sandwiched between two Co(100) films was investigated by x-ray magnetic circular dichroism (XMCD) at various temperatures. XMCD is a powerful technique due to its ability to probe element specific magnetization of the system. This study shows that fcc-Fe overlayers on Cu(100) exhibit out of plane magnetization and aligned ferromagnetically upto 4 monolayer (ML) thickness. The magnetization between 5 ML to 10 ML is complex with a very small total magnetic moment. The magnetization above 10 ML is in-plane concomitant to the change to bcc-structure as for bulk Fe. The magnetization direction of the fcc-Fe films changes to in-plane magnetization when deposited on Co(100). However, the thickness dependence of magnetization of Fe film remains unchanged. Interestingly, the dependence of the Fe magnetism on the film thickness is complex and qualitatively similar on Co(100) and in fcc-Co/Fe/Co(100) trilayers. This study, thus, rules out the possibility of various predictions suggesting ferromagnetic surface, sub-surface and/or interface layers contributing the observed magnetic moment with the inner layers to be paramagnetic or antiferromagnetic. The fcc-Fe film magnetization is found to present a pronounced oscillation. The decrease in temperature down to 100 K does not exhibit any change in the magnetic properties of the Fe-film. The fcc-Fe films mediate an oscillatory, indirect coupling in Co/Fe/Co(100) structures that alternates in correspondence with the changes of the Fe magnetization.