Magnetization and coercivity studies in amorphous Nd/sub 50/Fe/sub 50//BN multilayers

Amorphous Nd/sub 50/Fe/sub 50//BN multilayers are fabricated by sputtering over a wide range of bilayer thickness. A superparamagnetic behavior is found above 20 K in samples with a d/sub NdFe/ thickness below 15 AA which may be due to the particulate like nature of the thinner films. In samples with d/sub NdFe/ above 15 AA, the spontaneous magnetization is found to be independent of thickness. The coercivity increases with the NdFe layer thickness according to 1/d/sub NdFe/. This may be related to the out of plane effective surface anisotropy. The spontaneous magnetization does not follow Bloch's law above 50 K. A linear temperature dependence is observed in the temperature range of 50-300 K, with the temperature range extending to lower temperature in samples with thinner NdFe layers.<
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