Shield-related Side Reading In MR Heads

Shield-related side reading of recorded data tracks by shielded MR heads is investigated. This phenomenon is caused by the magnetic coupling between the shields and MR elements. Changes in the magnetic states in the shields can either make the side reading appear or disappear. The linear density of the recorded pattern has a strong effect on the degree of the phenomenon. In reading the synchronization patterns in the servo field of a hard disk drive, this kind of MR head can produce a read-back signal with severe distortion, causing the drive to malfunction. Improved shield structure can significantly reduce this side reading.