Suppression of in-plane (001) texture component in FePt-oxide granular films by adding a carbon buffer layer

Investigation of magnetic properties and nanostructure of FePt-B2O3 granular film with carbon buffer layer (BL) of various thicknesses is reported. When the thickness of carbon BL is varied from 0 to 0.6 nm, saturation magnetization (Msfilm) is almost constant at around 750 emu/cm3 and perpendicular magnetic anisotropy (Ku⊥film) changes from around 1.0×107 to 2.0×107 erg/cm3. For the granular film with the carbon BL thicker than 0.6 nm, both Msfilm and Ku⊥film decrease. The reduction of Msfilm for the granular film by adding a carbon BL may be due to the alloying of carbon into the FePt magnetic grains. The enhancement of Ku⊥film for the film with a 0.6 nm carbon BL is considered due to the reduction of the in-plane texture component which is supported by the in-plane XRD. The reduction of Ku⊥film for the film with a carbon BL thicker than 0.6 nm is considered due to random growth of magnetic grains on a continuous carbon BL which is supported by the TEM cross-section images. According to these results, the employment of an un-continuous thin carbon BL is a promising method to enhance c-axis texture orientation of the FePt-oxide granular films.