Structure, ferromagnetic resonance, and permeability of nanogranular Fe-Co-B-Ni films

Abstract

The static and microwave magnetic properties of soft nanogranular (Fe(0.7)Co(0.3))(71)B(22)Ni films with a 2 T saturation magnetization are presented as functions of thickness, ranging from 136 to 235 nm. Microwave permeability values from 60 to 260 are measured and ferromagnetic resonance frequencies up to 6.8 GHz are found using a vector network analyzer, connected to coplanar/microstrip structures loaded with the ferromagnetic films. Topographic and magnetic structures down to 20-40 nm were observed by atomic/magnetic force microscopy. The combination of reasonable values of the permeability and high ferromagnetic resonance frequency makes these nanogranular materials useful in the development of inductive microwave components. (C) 2006 American Institute of Physics.