Perpendicular Recording Media With Patterned Magnetic Underlayer to Reduce Readback Signal Envelope Modulation
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Perpendicular recording media for use with pole-type head configurations commonly employ two layers: a magnetic storage layer with perpendicular anisotropy and a soft-magnetic underlayer to provide a flux return path for the head, as depicted in Fig. 1. The magnetic storage layer is typically a thin film cobalt-chromium (CoCr) alloy or a coating of barium ferrite particles dispersed in an organic binder. The underlayer is typically a nickel-iron (NiFe) alloy. In order to reduce the readback signal envelope modulation resulting from in-plane anisotropy in the underlayer, the underlayer should be made as nearly isotropic as possible.