Read sensor having a structure for reducing magnetic coupling between a magnetic bias layer and an upper magnetic shield

Abstract

A magnetic sensor having reduced read gap thickness, reduced signal noise and improved signal to noise ratio. The sensor includes a sensor stack and hard bias structures formed at either side of the sensor stack for biasing the free layer of the sensor. A protective layer is formed over a portion of the hard bias structure, however a portion of the hard bias structure extends upward toward the upper shield and is disposed between the protective layer and the sensor stack as a result of the process used to form the magnetic bias structure. This portion of the hard bias structure that extends toward the upper shield has a reduced magnetization relative to the rest of the hard bias structure so that it will not magnetically couple with the upper shield.

Dependencies are inferred from the claim text.