Nanogranular$L 1_0$FePt:C Composite Films for Perpendicular Recording

Nano-granular L1
₀
FePt:C composite films with perpendicular anisotropy were in situ deposited on glass substrates at 350degC by dc magnetron sputtering. The magnetic, microstructural, and recording properties of the FePt:C perpendicular media were investigated. A good FePt (001) texture was maintained after incorporating up to 20 vol.% C, the measured full-width at half-maximum (FWHM) of the rocking curves of the FePt (001) peak slightly increased from 7.2deg to 8.5deg. FePt:C (20 vol.% C) films consisted of a continuous layer of FePt, with overlying granular FePt grains (5.6 nm) that were well separated by carbon. H
_c
increased from about 2600 to 3700 Oe with increasing C concentration from 0 to 15 vol.%, and then decreased with further increasing C concentration. The exchange coupling did not show obvious change with increased carbon content up to 20 vol.% due to the strong coupling between continuous layer and overlying granular FePt grains, which resulted in the overlap and fluctuation of recorded signals at a linear density of 221 kfci