Patent ID: 8031445
Filing Date: 2011-10-04
Classification: B82Y,G11B

Abstract:
1. A method to manufacture a magnetic sensor, comprising: depositing, in unbroken succession on a substrate, a first magnetic free layer, having a thickness and a composition, a non-magnetic layer having a thickness and a composition, and a second magnetic free layer, having a thickness and a composition, thereby forming a sensor stack; patterning said sensor stack to form a sensor that has, when viewed from above, an approximately rectangular shape with a short dimension SH and a long dimension TW; dimensioning SH and TW so that SH has a value that is from ⅓ to ⅔ that of TW; adjusting the thickness and the composition of said non-magnetic layer so as to minimize ferromagnetic coupling between said first and second magnetic free layers, thereby reducing noise in a signal generated by said magnetic sensor; adjusting said thicknesses and compositions of said magnetic free layers whereby there is a net antiparallel magnetic coupling between said magnetic free layers; depositing and then patterning a layer of magnetically hard material to form a permanent magnet that is located a distance from said sensor; and permanently magnetizing said permanent magnet to a sufficient extent to cause said free layers to be magnetized in directions that are approximately orthogonal to one another.