Michael Paul Salo

Dependence of magnetoresistive head readback characteristics on sensor height

The microtrack profile and bias point of a magnetoresistive (MR) head play a fundamental role in determining the full track response. In this paper the stripe height dependence of these properties is studied. The magnetic center of the MR head is found to approach the physical center, and microtrack side slopes become steeper and more equal as the stripe height is decreased. These experimentally observed trends can be understood using a simple model based on anisotropic flux propagation in the MR sensor.

Write induced track misregistration due to magnetic center shifts in thin film inductive heads

The effect of writing on track misregistration in thin film heads for hard disk drives is discussed. An experimental technique is presented which shows that writing causes changes in the magnetic state of the head. These magnetic changes are interpreted by the servo channel as shifts in the position of the head. Real track misregistration occurs as the servo tries to compensate. Typical variations in head position have a standard deviation of 2 to 4 microinches. From ontrack testing of a known unstable head it is concluded that unstable waveforms do not necessarily indicate a magnetic center shift. The opposite behavior has also been seen: magnetic center shifts occur with no noticeable change in waveform. >