Perpendicular magnetic recording medium with single domain exchange-coupled soft magnetic underlayer and device incorporating same

A method of producing a magnetic recording medium with a single domain soft magnetic underlayer, comprising:

• depositing a first soft ferromagnetic layer above a substrate;
• depositing a first spacer layer above said first soft ferromagnetic layer;
• depositing a second soft ferromagnetic layer above said first spacer layer;
• depositing a second spacer layer above said second soft ferromagnetic layer;
• depositing a third soft ferromagnetic layer above said second spacer layer, wherein a material of one of the first soft ferromagnetic layer, the second soft ferromagnetic layer, and the third soft ferromagnetic layer is different from a material of another of the first soft ferromagnetic layer, the second soft ferromagnetic layer, and the third soft ferromagnetic layer;
• whereby the product of saturation magnetization (Ms) and thickness (t), Mst, of the second soft ferromagnetic layer is less than the sum of the Mst of the first soft ferromagnetic layer and the Mst of the third soft ferromagnetic layer;
• and
• performing a radial field reset such that said first soft ferromagnetic layer assumes a first remanent radial magnetic orientation, said second soft ferromagnetic layer assumes a second remanent radial magnetic orientation anti-parallel to said first remanent radial magnetic orientation, and said third soft ferromagnetic layer assumes said first remanent radial magnetic orientation.