Magnetization and coercivity studies in amorphous Nd50Fe 50/BN multilayers

Amorphous Nd₅₀Fe₅₀/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_NdFe thickness below 15 Å which may be due to the particulate like nature of the thinner films. In samples with d_NdFe above 15 Å, the spontaneous magnetization is found to be independent of thickness. The coercivity increases with the NdFe layer thickness according to 1/d_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