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In the last decade, the magnetism of ultrathin films and nanostructures has been a field of intense research. This mainly due to the fact that magnetic properties of such objects often deviate strongly from the properties of the bulk material. This can lead to a new physical phenomena as, e.g., oscillating exchange coupling of ferromagnetic films across nonferromagnetic spacer layers. The Fe/Cr/Fe(001) system is one of the most intensively studied magnetic multilayer systems where a short and a long periods of oscillatory coupling between the Fe layers were found of 2ML and ~18Å, respectively. The observed long-period for three orientations ((100), (211), and (110)) suggests that there may be a common origin for coupling in all three cases. In some sense it can be assigned to the fact that at the Cr/Fe interface, for minority electrons, the reflection is weak for most of the electrons, because the Fe minority Fermi surface is very similar to that of Cr. For the majority electrons, the reflection is much more complicated, and depends more strongly on interface orientation.
The vast majority of chromium thin films and multilayers studied to date have been oriented in a <100> direction. A much little attention was paid to the Fe/Cr/Fe(110) system that is somewhat surprising since at Cr/Fe(110) interface no interdiffusion occurs at room temperature in contrast to the observations for (100)-oriented interface. Recent theoretical works explain observation of long-period as well as predict the short-period oscillations with a period of 4.7Å in (110)-oriented Cr film.
The aim of the present work is an attempt to find such short-period oscillations in (110)-oriented thin Cr films by spectroscopic method. Here we present, for the first time, the high quality spin-resolved photoelectron spectroscopy study of the Cr/Fe(110) interface. The system was investigated at room temperature for different thicknesses of Cr overlayer. As a result, we observe the initial fast drop, followed by a weak oscillatory behavior, of the photoelectron spin-polarization (P) at the Fermi level, EF. The observed period of weak oscillations of P give an evidence for the first time observation of short-period oscillations in Cr(110) oriented thin films. |