Non linear magnetoresistive sensor

Claim 1

Apparatus comprising: a magnetoresistive sensor mounted in a recording head adjacent a magnetic recording medium comprising: a sense region having a magnetization vector M aligned parallel to the easy axis in the absence of external magnetic fields from said recording medium; means for providing a sense current in the sense region having a vector J substantially parallel with said easy axis magnetization vector M; said magnetic recording medium mounted adjacent to said head such that relative motion between them can occur; the magnetic medium having a plurality of magnetization transitions recorded thereon providing magnetic flux pulses to the sense region as a transition passes the sensor, the peak flux amplitude of the pulse being sufficient to rotate the sense region magnetization vector M away from the sense current vector J so that the angle between them is in the range of 40 to 50 degrees, whereby the sensor operates in a non linear mode because of the initial alignment of sense current and magnetization vectors in absence of magnetic flux from the magnetic medium, and wherein the sensor's response in the region of the pulse peak from magnetic flux from the magnetic medium is approximately a linear function of magnetic flux of the transition.