High magnetic field sensitivity of TbFeCo layer and Pt/Co multilayers with an ultra-thin RE-rich RE-TM layer

We studied the magnetic field sensitivity of double layer disks which were composed of a TbFeCo recording layer with low Tb content and a high-T/sub c/ RE-rich DyFeCo ultra-thin layer. The Tb/sub 14/Fe/sub 82/Co/sub 4//Dy/sub 30/Fe/sub 35/Co/sub 35/ double layer disk has better magnetic field sensitivity than a TbFeCo single recording layer disk. It was found that the film having such a large magnetization as Tb/sub 14/Fe/sub 82/Co/sub 4/ can be used for MO materials. Furthermore, we investigated the Pt/Co multilayers as a recording layer with an ultra-thin RE-TM layer. The addition of the ultra-thin RE-rich TbCo layer on the Pt/Co multilayers is effective for improvement of the C/N and the field sensitivity as well as that on the TbFeCo recording layer.