EFFECTS OF OXIDE ADDITION ON MAGNETIC AND STRUCTURAL-PROPERTIES OF CONIPT ALLOY-FILMS

The effects of oxide addition on magnetic and structural properties of sputtered CoNiPt alloy films for high density longitudinal recording with a random c-axis orientation of hcp Co have been studied. It is found that the addition Of SiO2 UP to 4.2 at. % results in a significant increase in the in-plane coercivity from 1700 to 2400 Oe and a signal to media noise ratio with a slight decrease in coercive squareness from 0.90 to 0.87, while the perpendicular magnetic anisotropy is not significantly changed. X-ray diffraction shows that the c-axis orientation normal to the film plane does not change and the hcp lattice is strained due to the addition of SiO2. A marked decrease in the grain size is observed with the addition of 4.2-at. % SiO2, which causes the development of grain separation and therefore enhances the coercivity. The origin of the increase in coercivity with 2.1-at. % SiO2 is also discussed.