Patent ID: 8728825
Filing Date: 2014-05-20
Classification: B82Y,G01N,G01R,Y10T

Abstract:
1. A method of forming a sensitive GMR sensor stripe having a stable bias point under the effects of magnetic hysteresis during periods of quiescence, comprising: providing a substrate; forming on said substrate a horizontally layered GMR sensor stripe having a planar rectangular shape that is longer along its length dimension than its width dimension, said stripe comprising a magnetically free layer having a coefficient of magnetostriction that is adjustable by variations in its dimensions and composition, a magnetically pinned layer and a non-magnetic, electrically conducting spacer layer therebetween whereby a shape induced magnetic anisotropy along said length dimension is produced in said pinned and said free layers; surrounding said sensor stripe with contiguous insulating layers, the formation of said contiguous layers placing the stripe in a condition of anisotropic compressive or tensile stress along said width dimension; setting the magnetic moments of said magnetically pinned and magnetically free layers in the direction of their lengths, said shape induced magnetic anisotropy along said length dimension thereby serving to stabilize the bias point of said magnetic moment of said free layer along said length dimension during periods of quiescence against the effects of hysteresis; then reducing the overall magnetic anisotropy of said magnetically free layer by combining with said shape anisotropy in said length dimension said stress induced anisotropy in said width dimension obtained by an adjustment of said coefficient of magnetostriction combined with said tensile or compressive stresses along said width dimension, thereby enhancing the sensitivity of said sensor stripe during operation while maintaining said stable bias point during quiescence.