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US 5,701,222 AGranted
Spin valve sensor with antiparallel magnetization of pinned layers
AssigneeInternational Business Machines Corporation
InventorsHardayal Singh Gill, Bruce A. Gurney
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Abstract
A magnetoresistive (MR) sensor comprises a dual differential spin valve structure. Each of the spin valves comprise first (free) and second (pinned) layers of ferromagnetic material separated by a thin film layer of nonmagnetic material. The magnetization direction of the pinned layers of ferromagnetic material in each spin valve is fixed, and their magnetization is set antiparallel to each other. A current flow is produced through the MR sensor, and the variations in voltage across the MR sensor are sensed due to changes in resistance of the MR sensor produced by rotation of the magnetization in the free layers of ferromagnetic material as a function of the magnetic field being sensed.
Claims10
A magnetic disk recording system comprising:
- a magnetic storage medium having a plurality of tracks for recording of data;
- a magnetic transducer maintained in a closely spaced position relative to said magnetic storage medium during relative motion between said magnetic transducer and said magnetic storage medium, said magnetic transducer including a magnetoresistive read sensor comprising:
- a first and a second layered structure, said first and second layered structure separated by a nonmagnetic antiferromagnetic spacer layer, said spacer layer having a high electrical resistivity;
- each of said layered structures comprising free and pinned layers of ferromagnetic material separated by a layer of nonmagnetic material, said first layered structure pinned layer further including a first and second layer of ferromagnetic material separated by an antiferromagnetic nonmagnetic coupling layer;
- a layer of antiferromagnetic material in contact with said second layered structure pinned layer for fixing the magnetization direction of said second layered structure pinned layer, the magnetization in said layer of antiferromagnetic material being in parallel with the magnetization in said nonmagnetic antiferromagnetic spacer layer;
- said magnetization direction of said second layer of ferromagnetic material in said first layered structure pinned layer being fixed by said nonmagnetic antiferromagnetic spacer layer in a direction antiparallel to the magnetization direction of said second layered structure pinned layer and said magnetization direction of said first layer of ferromagnetic material in said first layered structure pinned layer being fixed in a direction parallel to the magnetization direction of said second layered structure pinned layer;
- means for producing a current flow through said magnetoresistive sensor;
- and
- said magnetoresistive sensor producing variations in its resistivity in response to an external magnetic field due to rotation of the magnetization in said free layers of ferromagnetic material in each of said layered structures;
- actuator means coupled to said magnetic transducer for moving said magnetic transducer to selected tracks on said magnetic storage medium;
- and
- detection means coupled to said magnetoresistive read sensor for detecting resistance changes responsive to magnetic fields representative of data bits recorded in said magnetic storage medium intercepted by said magnetoresistive sensor.
9 more elements
A dual magnetoresistive sensor comprising:
- a first and a second layered structure, said first and second layered structures separated by a nonmagnetic antiferromagnetic spacer layer, said spacer layer having a high electrical resistivity;
- each of said layered structures comprising free and pinned layers of ferromagnetic material separated by a layer of nonmagnetic material, said first layered structure pinned layer further including a first and second layer of ferromagnetic material separated by an antiferromagnetic nonmagnetic coupling layer;
- a layer of antiferromagnetic material in contact with said second layered structure pinned layer for fixing the magnetization direction of said second layered structure pinned layer, the magnetization in said layer of antiferromagnetic material being in parallel with the magnetization in said nonmagnetic antiferromagnetic spacer layer;
- said magnetization direction of said second layer of ferromagnetic material in said first layered structure pinned layer being fixed by said nonmagnetic antiferromagnetic spacer layer in a direction antiparallel to the magnetization direction of said second layered structure pinned layer and said magnetization direction of said first layer of ferromagnetic material in said first layered structure pinned layer being fixed in a direction parallel to the magnetization direction of said second layered structure pinned layer;
- means for producing a current flow through said magnetoresistive sensor;
- and
- means for sensing the variations in the resistivity of the magnetoresistive sensor in response to an external magnetic field due to rotation of the magnetization in said free layers of ferromagnetic material in each of said layered structures.
4 more elements
Dependencies are inferred from the claim text.