Effects of oxide addition on magnetic and structural properties of CoNiPt alloy films

Abstract

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.