Hard-film stabilized soft-film biased magnetoresistive sensor with an alumina under layer pattern for improved longitudinal servo- positioning linearity and stability

摘要

A magnetoresistive sensor design and fabrication process that provides improved microtrack profile linearity for servo elements while simultaneously providing stable and linear data sensing elements suitable for high density tape head applications. The stability and uniformity of both data and servo sensor elements is enhanced through the use of a grating profile under both the soft film biased magnetoresistive sensor layer and the hard bias stabilizing magnets. Processing steps are eliminated by replicating the grating pattern for the servo sensor elements through a thick layer of alumina or silicon dioxide. The outer read shield is removed from the servo elements using a stripping process that eliminates structural damage arising from alumina pinholes. Both element types are free of significant Barkhausen noise and instability because of the grating-stabilized domains in both the active magnetoresistive regions and the passive hard-biasing regions of each sensor. Each servo sensor is disposed at a greater distance from the single shield to optimize the microtrack profile. The resulting reduction in servo sensor frequency response leaves sufficient bandwidth for precise servo positioning.