Brinks Hofer Gilson & Lione
Spin-valve magnetoresistive sensor including a first antiferromagnetic layer for increasing a coercive force and a second antiferromagnetic layer for imposing a longitudinal bias
The present invention provides a spin-valve magnetoresistive sensor comprising at least two ferromagnetic layers including a first and a second ferromagnetic layers. A first antiferromagnetic layer is layered adjacent to the first ferromagnetic layer for increasing the coercive force of the first ferromagnetic layer to pin the magnetization direction of the first ferromagnetic layer. A pair of second antiferromagnetic layers are respectively positioned adjacent to the longitudinal ends of the second ferromagnetic layer. Further, a pair of third ferromagnetic layers are respectively layered adjacent to said pair of second antiferromagnetic layers for inducing magnetic anisotropy to pin the magnetization direction of each third ferromagnetic layer in a direction perpendicular to the pinned magnetization direction of the first ferromagnetic layer, thereby imposing a longitudinal bias on the second ferromagnetic layer to stabilize magnetic domains therein in order to suppress Barkhausen noise. The magnetization direction of the second ferromagnetic layer remains free to rotate in accordance with the direction of an external magnetic field, thereby changing the electrical resistance of the sensor.
Alps Electric Co., Ltd.
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Akihiro Masamichi Naoya
Makino Saito Hasegawa