Patent ID: 7070870
Filing Date: 2006-07-04
Classification: G11B,Y10T

Abstract:
1. A magnetic disk drive comprising: a magnetic disk containing recorded dare; a read-write head; and a motor coupled to rotate said magnetic disk at a rotational velocity during ordinary operation of said disk drive; said magnetic disk comprising: a substrate; a lower magnetic layer structure formed over the substrate; an intermediate layer comprising Ru; and an upper magnetic layer structure formed over the intermediate layer, said upper magnetic layer structure being antiferromagnetically coupled to the lower magnetic layer structure, wherein the relationship between the dynamic coercivity of the lower magnetic layer structure and the exchange field is such that after termination of application of a write magnetic field to the usable locations on the disk the portion of the lower magnetic layer structure at said locations achieve substantially their steady magnetization state within the time required for one revolution of said disk when said disk is being rotated at said rotational velocity.