Low energy C+ ion embedment induced structural disorder in L1 FePt

Abstract

Shallow embedding of C+ ions (<2 nm) into commercial CoCrPt-based magnetic media using the filtered cathodic vacuum arc technique improves its anti-oxidation and anti-wear properties which are comparable to the conventionally used thicker carbon overcoats of ∼3 nm. The next generation L10 FePt media subjected to low energy embedment of C+ ions have the potential to provide reduced magnetic spacing along with smaller and thermally stable grains, which is pivotal for achieving areal densities beyond 1 Tb/in.2 However, the impact of low energy C+ ions embedding on the magnetics of FePt media is not known. Here, the magnetic properties of L10 FePt, post-shallow C+ ion embedment at 350 eV, were investigated. It was observed that bombardment of C+ ions in the 5 nm thick FePt films produced a monumental reduction of ∼86% in the out-of-plane coercivity value. Increasing the FePt film thickness did not significantly suppress the impact of these C+ ions on the media. Structural and elemental analyses attributed this alteration caused in the magnetic properties of the well-ordered FePt films to the penetration of >2 nm by the C+ ions into the FePt film. The media's crystallography with respect to the size and direction of the incoming ions has emerged to be accountable for the deeper distribution of the C+ ions and the associated widespread cascade damages within the magnetic layer. The consequences of low energy C+ ions embedding to attain high storage densities using high anisotropy L10 FePt media are discussed.