THIN FILM PERMANENT MAGNET FOR PRE-MAGNETIZING THE HEAVY AND LIGHT AXES OF AN MR MAGNET HEAD.

摘要

A previously disclosed "C" shaped thin film deposited permanent magnetic structure of essentially symmetrical form is designed to provide a planar region of transverse field with little or no longitudinal field component. Practice of the present invention teaches asymmetrically modifying the "C" shaped magnet to restore a small controlled amount of unidirectional longitudinal field component. The symmetry is broken by either angling the direction of magnetization of the magnet relative to the symmetric geometric form of the structure, or by angling the direction of the magnetization and also changing the geometric shape of the magnet from a "C" shape to an "L" shape. The resultant field distribution of the deposited asymmetrical magnetic structure produces a magnetic field of sufficient strength for biasing the hard axis of a coplanarly deposited MR element with an additional relatively smaller magnitude unidirectional easy axis field for longitudinally biasing it. The hard axis bias field magnitude decreases across the width of the magnetoresistive element. Thus, as the head wears and the magnetoresistive element resultantly decreases in width, the average hard axis field across the element increases in magnitude, automatically compensating for the increasing demagnetization fields in the magnetoresistive element.