The Effects of P and Pt on the Microstructure of Co-Cr-P-Pt Thin Film Magnetic Recording Media

Abstract

Because of their high coercivity, cobalt alloy thin films are among the most popular materials used for ultra-high density longitudinal magnetic recording media. The recording and magnetic properties of the materials are related to their microstructure; in particular, depletion of Co in a grain boundary phase, and physical separation of the grains act to increase coercivity and thus to produce low noise media. We are studying a new alloy system comprising 18 nm thick Co-Cr-P-Pt films (Mr.t ≈ 0.9 memu/cm2), prepared by DC sputtering. A coercivity of 2600 Oe or higher was obtained in these films even when they were deposited without heating the substrate or applying a bias voltage. The effects of P and Pt addition were characterized by high-resolution TEM coupled with energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). A Hitachi HF-2000 field emission TEM was used to image both low P (≈ 6 at. %) and high P (≈ 12 at. %) samples, and to provide a 1 nm beam for high spatial resolution EDS and EELS.