Improvement of read/write characteristics of sputtered Ba ferrite disks by adding Ta into Pt under layers

摘要

A magnetoplumbite type of Ba (BaM) ferrite films with superior chemical stability and mechanical hardness are promising candidates for perpendicular magnetic recording layers without protective layers. Excellent magnetocrystalline anisotropy constant of BaM ferrite films is an important merit for ultra-high density magnetic recording. It has been found that Pt underlayer is effective to promote the crystallinity and c-axis orientation of Ba ferrite films perpendicular to the film plane. However, Ba ferrite disks with Pt underlayers exhibited large dc erase noises and lower signal-noise ratio because of large grain size in the media. In this study, small amount of Ta was added into Pt underlayers to form fine grains in Ba ferrite layers.