Patent ID: 6833982
Filing Date: 2004-12-21
Classification: B82Y,G11B,Y10T

Abstract:
In a magnetic read head having an air bearing surface (ABS), a magnetic tunnel junction (MTJ) sensor for connection to sense circuitry for detecting changes in electrical resistance within the sensor, the sensor comprising:a MTJ stack with an active region disposed at the ABS and having oppositely facing first and second sides each disposed generally orthogonally to the ABS, the MTJ stack comprising: an antiferromagnetic (AFM) layer spanning the active region, a pinned layer of ferromagnetic (FM) material in contact with the AFM layer, a free layer of FM material spanning the active region and having first and second free layer extensions which extend in opposite directions from the first and second sides respectively; a tunnel junction layer of electrically nonconductive material disposed between the pinned layer and the free layer in the active region; the AFM, pinned, free and tunnel junction layers having parallel surfaces which extend between the first and second sides and are orthogonal with respect to the ABS; and the first and second free layer extensions having first and second top surfaces which are parallel with respect to the parallel surfaces of the AFM, pinned, free and tunnel junction layers; first and second longitudinal bias layers formed on and in contact with the first and second top surfaces of the free layer extensions outside of the active region for biasing the magnetic moment of the free layer in substantially a predetermined direction in the absence of an external magnetic field.