Patent ID: 6055136
Filing Date: 2000-04-25
Classification: B82Y,G01R,G11B

Abstract:
A magnetic disk recording system comprising:a magnetic storage medium having a plurality of tracks for recording of data;a magnetic transducer maintained in a closely spaced position relative to said magnetic storage medium during relative motion between said magnetic transducer and said magnetic storage medium, said magnetic transducer including a magnetoresistive read sensor, said magnetoresistive read sensor comprising:a first spin valve structure, comprising:a first ferromagnetic free layer;a first ferromagnetic pinned layer, said first pinned layer including a first and a second layer of ferromagnetic material separated from each other by an antiferromagnetic coupling layer, wherein said first pinned layer is the only pinned layer in said magnetoresistive read sensor having an antiferromagnetic coupling layer;a first nonmagnetic conductive spacer layer disposed between said first ferromagnetic free layer and said first ferromagnetic pinned layer; anda first layer of antiferromagnetic material in direct contact with said second layer of ferromagnetic material in said first pinned layer for fixing the magnetization direction of said first pinned layer;a second spin valve structure, comprising:a second ferromagnetic free layer;a second ferromagnetic pinned layer;a second nonmagnetic conductive spacer layer disposed between said second free layer and said second pinned layer; anda second layer of antiferromagnetic material in direct contact with said second pinned layer for fixing the magnetization direction of said second pinned layer;a nonmagnetic insulating spacer layer disposed between said first and second spin valve structures;a first and a second current source for producing current flows through said magnetoresistive sensor; andsaid magnetoresistive read sensor producing variations in its resistivity in response to an external magnetic field due to rotation of the magnetization in said free layers of ferromagnetic material in each of said first and second spin valve structures;actuator means coupled to said magnetic transducer for moving said magnetic transducer to selected tracks on said magnetic storage medium; anda recording channel coupled to said magnetoresistive read sensor for detecting resistance changes in said magnetoresistive read sensor responsive to magnetic fields representative of data bits recorded in said magnetic storage medium intercepted by said magnetoresistive read sensor.