Abstract: A perpendicular magnetic recording medium includes a hard magnetic recording layer and a soft magnetic underlayer adjacent the hard magnetic recording layer. The soft magnetic underlayer includes first and second ferromagnetically coupled multilayer structures and a coupling layer positioned between the first and second multilayer structures for antiferromagnetically coupling the first and second multilayer structures. A magnetic disc drive storage system incorporating such a perpendicular magnetic recording medium and a method of making such a perpendicular magnetic recording medium are also included.

Abstract: A method and apparatus for determining volume and anisotropy field distribution of thin film granular material includes the use of a magneto-optic probe, a lock-in amplifier, and a computer. The magneto-optic probe utilizes the Kerr effect in order to determine the transverse AC susceptibility of the sample. The Lock-in amplifier determines the complex parameters of the susceptibility as a function of the DC field and AC frequency. Separate distribution values of anisotropy field and grain volume can then be determined mathematically from the relationship of complex susceptibility parameters to the DC field strength.

Abstract: Magnetic films having magnetic regions and non-magnetic regions are disclosed. The film is subjected to ion irradiation in order to produce chemically disordered regions in the film. The irradiated disordered regions may correspond to the non-magnetic regions of the film. Alternatively, the irradiated disordered regions may correspond to the magnetic regions of the film. In one embodiment, portions of a magnetic CrPt3 film are converted to non-magnetic regions by irradiating the regions with boron ions which disorder the CrPt3 film in the treated regions. The film may be patterned into magnetic regions and non-magnetic regions for applications such as magnetic recording media in computer disc drive systems.

Abstract: A perpendicular magnetic recording medium includes a hard magnetic recording layer and a soft magnetic underlayer adjacent the hard magnetic recording layer. The soft magnetic underlayer includes first and second ferromagnetically coupled multilayer structures and a coupling layer positioned between the first and second multilayer structures for antiferromagnetically coupling the first and second multilayer structures. A magnetic disc drive storage system incorporating such a perpendicular magnetic recording medium and a method of making such a perpendicular magnetic recording medium are also included.