Perpendicular magnetic recording medium with exchange-coupled magnetic layers and improved coupling layer

Abstract

A perpendicular magnetic recording medium has an 'exchange-spring' type magnetic recording layer (RL) with an improved coupling layer (CL). The RL includes the first or lower ferromagnetic layer MAG, sometimes called the 'media' layer, the second or upper ferromagnetic layer MAG, sometimes called the “exchange-spring” layer, and the intermediate CL that provides ferromagnetic exchange coupling between MAGand MAG. The CL is formed of NiCr or RuCr based alloys, or CoCr or CoCrB alloys with high Cr and/or B content (Cr plus B>about 25 atomic percent), or RuCoCr alloys with low Co content (<about 65 atomic percent). For each CL composition there is a CL thickness range that provides the optimal interlayer exchange coupling between MAGand MAG. The selected CL materials provide an exchange-type perpendicular magnetic recording medium with good magnetic performance, while the relatively high amount of Cr of the CL improves the corrosion resistance of the medium.