Lateral magnetic inhomogeneities in Co-Cr layers detected by FMR

Co-Cr layers deposited on Ge underlayers were investigated with ferromagnetic resonance (FMR). The thickness of the Co-Cr layers and the substrate temperature (T/sub s/) during deposition were varied. Measurements with a vibrating sample magnetometer showed that an increase of T/sub s/ results in an increase of both the bulk saturation magnetization M/sub s/ and the perpendicular coercivity H/sub c//sup perpendicular to /. The FMR spectra, obtained with the applied field perpendicular to the sample, showed two resonances for all layers. The effective anisotropy field is positive for both resonances. The difference in effective anisotropy field does not change with thickness of the layer, but increases with increasing T/sub s/. From this it is clear that the two resonances are not due to magnetic inhomogeneities in the growth direction, but must be due to lateral magnetic inhomogeneities. Inhomogeneities in composition, resulting in different values of M/sub s/, or in geometric structure, resulting in different values of the demagnetizing factor N/sub d/, are the most probable causes of the observed effects.<
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