Patent ID: 6177207
Filing Date: 2001-01-23
Classification: G11B,Y10S,Y10T

Abstract:
A thin film magnetic head comprising:a magnetoresistive element layer;an electrode layer to impart a sensing current to the magnetoresistive element layer;a bottom core layer formed on the electrode layer via an insulation layer, the bottom core layer additionally being a top shield layer of a reading head;a top core layer confronting the bottom core layer at a confronting part of a recording medium via a magnetic gap; anda coil layer to impart a magnetic field to both core layers, said bottom core layer having a double-layer structure of soft magnetic films containing Co as a principal component and mainly composed of an amorphous structure with a composition formula of Co.sub.a Zr.sub.b Nb.sub.c, an upper side of the bottom core layer confronting the top core layer containing a higher concentration of Co than a lower side of the bottom core layer confronting the magnetoresistive element layer,wherein composition ratio a is in the range of 85.ltoreq.a.ltoreq.91 for the upper side bottom core layer,wherein composition ratio a is in the range of 78.ltoreq.a.ltoreq.82 for the lower side bottom core layer, andwherein composition ratios b and c are represented by;b=(0.5 to 0.8).times.(100-a) andc=100-a-bin both of the upper side bottom core layer and lower side bottom core layer.