Ion-beam sputtering has been used to prepare Fe/Si multilayers on a variety of substrates and over a wide range of temperatures. Small-angle x-ray diffraction and transmission electron microscopy experiments show that the layers are heavily intermixed although a composition gradient is maintained.When the spacer layer is an amorphous iron silicide, the magnetic properties of the multilayers are similar to those of bulk Fe. When the spacer layer is a crystalline silicide with the B2 or DO 3 structure, the multilayers show antiferromagnetic interlayer coupling like that observed in ferromagnet/paramagnet multilayers such as Fe/Cr and Co/Cu. Depending on the substrate type and the growth temperature, the multilayers grow in either the (011) or (001) 75.50. Bb,68.65.+g,81.15.Cd,75.30.E

Magnetization reversal processes in epitaxial NiO/NiFe bilayers were studied using the magneto-optic indicator film technique. The influence of dislocations on these processes was determined. Remagnetization parallel to the unidirectional anisotropy axis proceeds by domain nucleation and growth, with nucleation center activity being asymmetric with respect to the applied field sign. Magnetization reversal in the hard axis direction occurs by incoherent rotation. The enhanced coercivity and asymmetric nucleation can be explained by taking into account domain wall behavior in the antiferromagnetic layer.

001) oriented NiO/NiFe bilayers were grown on single crystal MgO (001) substrates by ion beam sputtering in order to determine the effect that the crystalline orientation of the NiO antiferromagnetic layer has on the magnetization curve of the NiFe ferromagnetic layer. Simple models predict no exchange anisotropy for the (001)-oriented surface, which in its bulk termina-

La0.8Sr0.2MnO3 thin films were simultaneously deposited by pulsed laser ablation on silicon (Si) and LaAlO3 (LAO) substrates. Films on Si were polycrystalline while those on LAO were (100) epitaxial with an in-plane correlation length of ≊10 nm. The magnetization and magnetoresistance behavior of these two films were significantly different. Both films exhibit antiferromagnetic–ferromagnetic transitions—at different temperatures [180 K (LAO); 230 K (Si)]—and their magnetic moments at 10 K were significantly different (Si—0.0035 emu; LAO—0.0022 emu). However, both films showed significant high field slope in magnetization at 10 K. Significant fractions of both films remain antiferromagnetic at low temperatures and hence net susceptibilities, dependent on the direction of the applied magnetic field, are different for the epitaxial (LAO) and randomly oriented polycrystalline (Si) films. The magnetoresistance peak, corresponding to the semiconductor–metal transition is observed at 170 and 130 K for the epitaxial (LAO) and polycrystalline (Si) films, respectively. Moreover, their resistance values are two orders of magnitude different (Si—MO/hms; LAO—KOhms). These properties can be interpreted in terms of the major role of grain boundaries in determining the scattering as well as possible differences in O2 stoichiometry.

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