Patent ID: 7154716

Claim:
A magnetic tunnel junction (MTJ) sensor device, comprising: a first lead layer; a sensor including; a pinned layer, a free layer adjacent to the pinned layer, the magnetization direction of the pinned layer being substantially perpendicular to the magnetization direction of the free layer at zero applied magnetic field, a tunnel barrier layer positioned between the pinned layer and the free layer, wherein the pinned layer, the free layer, and the tunnel barrier layer define a track width; a second lead layer, where the pinned layer, the free layer, and the tunnel barrier layer are positioned between the first lead layer and the second lead layer, the first lead layer and the second lead layer adapted for conducting a current through the sensor; a pair of hard bias layers adjacent to the pinned layer, the free layer, and the tunnel barrier layer for generating a hard bias magnetic field; and insulating layers positioned between the hard bias layers and the first lead layer and the second lead layer; wherein a sensor magnetic field generated by the current is opposite the hard bias magnetic field at a center of the track width of the sensor, wherein a thickness of each of the hard bias layers is at least five times a thickness of the free layer of the sensor.