High density magnetic recording medium

摘要

The invention relates to a method of producing a magnetic material for use in an ultrahigh density magnetic recording medium and to the medium itself. The method general includes the steps of vaporing a ferromagnetic lanthanide rare earth, growing clusters of the ferromagnetic lanthanide rare earth at a temperature below the temperature at which the ferromagnetic lanthanide rare earth forms locked-moment clusters, filtering superparamagnetic clusters from locked-moment clusters, and collecting the locked-moment clusters. Preferably, the ferromagnetic lanthanide rare earth is a ytterbium rare earth. Advantageously lanthanide alloys, mixtures of lanthanide rare earths and alloys of a mixture of lanthanide rare earths can be used. The filtering employs a gradient magnetic field to separate superparamagnetic clusters from moment-locked clusters. The gradient field magnet separates the superparamagnetic clusters which deflect by a large amount from the locked-moment clusters which deflect by a small amount. The separated moment-locked clusters are co-deposited on a substrate with an inert material such as SiO2. The clusters can be deposited on a substrate in the presence of a magnetic filed transverse to the substrate to form a magnetic recording medium.