Control of the static and high-frequency magnetic properties of perpendicular anisotropic Co-HfN granular films through insertion of HfN interlayers

We propose a multilayer granular structure wherein Hf-nitride (HfN) interlayers are inserted into Co-HfN granular films with perpendicular magnetic anisotropy (PMA) to control their static and high-frequency magnetic properties. The transition between soft ferromagnetic properties and PMA was achieved by varying the thickness of Co-HfN layers (2-30 nm) and HfN interlayers (1-4 nm). The resonance frequency of the Co-HfN (24 nm)/HfN films decreased from 2 to 0.9GHz with increasing HfN interlayer thickness, owning to the separation of the columnar granules and reduced interlayer interaction between Co-HfN granular layers via a HfN interlayer. (C) 2017 The Japan Society of Applied Physics