Mossbauer-effect studies of multilayers and interfaces

The usefulness of Mossbauer spectroscopy for the investigation of magnetic multilayer systems is described. By applying Fe-57 Mossbauer spectroscopy, the behavior of ultrathin magnetic layers, such as FCC-like Fe films on Cu(0 0 1). is studied. Position-specified (depth-selective) information is available by preparing samples in which monatomic Fe-57 probe layers are placed at specific vertical positions, e.g. at interfaces or at the surface. As demonstrated for egitaxial chemically ordered Fe50Pt50 alloy films and polycrystalline nanostructured Tb/Fe multilayers, the Fe-spin structure can be determined directly, and a site-selective Fe-specific magnetic hysteresis loop can be traced in very-highcoercivity materials. For the studies of non-magnetic layers, on the other hand, hyperfine field observations by Au-197 and Sn-119 probes are worthwhile. Spin polarizations in Au layers penetrating from neighboring ferromagnetic 3D layers are estimated from Au-197 Mossbauer spectra and are also studied by inserted Sn-119 probes in Au/3D multilayers. In the Sn spectra for Cr/Sn multilayers, it was found that remarkably large spin polarization is penetrating into Sn layers from a contacting Cr layer, which suggests that Cr atoms in the surface layer have a ferromagnetic alignment. (C) 1999 Elsevier Science B.V. All rights reserved.