Magnetoresistive sensor based on the spin valve effect
First Claim
1. The magnetoresistive sensor comprising:
- a first and a second thin film layer of ferromagnetic material separated by a thin film layer of non-magnetic metallic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field;
means for fixing the magnetization direction of said second layer of ferromagnetic material;
means for producing a current flow through said magnetoresistive sensor; and
means for sensing the variations in the resistivity of said magnetoresistive sensor due to rotation of the magnetization in said first layer of ferromagnetic material as a function of the magnetic field being sensed.
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Abstract
A magnetoresistive (MR) sensor comprising a first and a second thin film layer of a magnetic material separated by a thin film layer of a non-magnetic metallic material. The first ferromagnetic layer is magnetically soft. The magnetization direction of the first layer of magnetic material is set substantially perpendicular to the magnetization of the second layer of magnetic material at zero applied field, and the magnetization direction of the second layer of magnetic material is fixed. 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 first layer of magnetic material as a function of the magnetic field being sensed. The variation of the resistance with the angle between the magnetizations of the first and second layers of magnetic material has been defined as the spin valve (SV) effect. It is also shown that, by a suitable direction of the current with respect to the fixed magnetization, the (SV) magnetoresistance can be added constructively to the usual anisotropic magnetoresistance.
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Citations
16 Claims
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1. The magnetoresistive sensor comprising:
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a first and a second thin film layer of ferromagnetic material separated by a thin film layer of non-magnetic metallic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; means for fixing the magnetization direction of said second layer of ferromagnetic material; means for producing a current flow through said magnetoresistive sensor; and means for sensing the variations in the resistivity of said magnetoresistive sensor due to rotation of the magnetization in said first layer of ferromagnetic material as a function of the magnetic field being sensed. - View Dependent Claims (3, 4, 5, 7, 9, 11, 14, 15, 16)
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2. A magnetoresistive sensor comprising:
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a first and a second layer of ferromagnetic material separated by a layer of non-magnetic metallic material, the magnetization direction of said first layer of ferromagnetic material being substantially perpendicular to the magnetization direction of said second layer of ferromagnetic material at zero applied magnetic field; means for producing a longitudinal bias sufficient to maintain said first layer of ferromagnetic material in a single domain state; means for producing a current flow through said magnetoresistive sensor; and means for sensing the variations in the resistivity of said magnetoresistive sensor due to the difference in rotation of the magnetizations in said first and second layers of ferromagnetic materials as a function of the magnetic field being sensed. - View Dependent Claims (6, 8, 10, 12, 13)
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Specification