Patterned MR Device with Controlled Shape Anisotropy

摘要

A magnetic sensor with increased sensitivity, lower noise, and improved frequency response is described. The sensor's free layer is ribbon shaped and is closely flanked at each long edge by a ribbon of magnetically soft, high permeability material. The side stripes of soft magnetic material absorb external field flux and concentrate the flux to flow into the sensor's edges to promote larger MR sensor magnetization rotation. Side stripes may be located in the plane of the free layer a maximum distance of 0.1 microns, above a plane that includes a top surface of the free layer, or below a plane that includes the bottom surface of the magnetic sensor. Edges of each side stripe may be aligned above or below a portion of the magnetic sensor.

主权项

1. A magnetic sensor, comprising:
a magnetoresistive (MR) device comprising a plurality of layers and patterned in the form of a MR stripe having a first bottom surface, a top layer that is a magnetically free layer having a first top surface, a first thickness, an aspect ratio of at least 5, and a pair of opposing first edges that are equidistant from a center plane that bisects the MR stripe in a lengthwise direction that is perpendicular to a width of the free layer along a second direction; and a pair of flux absorbing stripes made of a magnetic material and each having a second edge facing the center plane and a side of the MR stripe and aligned parallel to the opposing first edges, a second top surface, a second bottom surface, and a second thickness, and wherein a product of flux absorbing stripe magnetization times the second thickness is greater than a product of free layer magnetization times the first thickness, and each of the second edges is offset from one of the opposing first edges of the free layer by a first distance along the second direction.