High frequency initial permeability of NiFe and FeAlN

The initial permeability of NiFe single layer films and single and multi-layer FeAlN films up to 500 MHz are presented. The permeability of thin (<1500 Å) NiFe and FeAlN films were fit with calculations based on the Landau-Lifshitz/Gilbert model for phenomenological damping, using damping factors of ~0.016 and ~0.026, respectively. Transverse bias permeability measurements identified larger ripple fields in FeAlN samples compared to those in thin NiFe samples. The permeability of ~2 μm thick NiFe and FeAlN films were well described by eddy current theory. The permeability roll off frequency of 2 μm thick patterned FeAlN films Increased from 20 to 200 MHz when laminated into 32 layers separated by 25 Å thick SiN interlayers