Abstract A magnetoresistive (MR) sensor comprising a layered structure formed on a substrate (11) includes a first (12) and a second (16) thin film layer (14) of magnetic material separated by a thin film layer of non-magnetic metallic material such as Cu, Au, or Ag, with at least one of the layers of ferromagnetic material formed of either cobalt or a cobalt alloy. The magnetization direction of the first ferromagnetic layer, at zero applied field, is set substantially perpendicular to the magnetization direction of the second ferromagnetic layer which is fixed in position. A current flow is produced through the sensor, and the variations in voltage across the MR sensor are sensed due to the changes in resistance produced by rotation of the magnetization in the front layer of ferromagnetic material as a function of the magnetic field being sensed. <IMAGE>
A magnetoresistive sensing apparatus including, a magnetoresistive sensor comprising: a substrate; a first thin film layer of ferromagnetic material formed on the substrate; a thin film layer of non-magnetic metallic material formed on the first thin film layer of ferromagnetic material; a second thin film layer of ferromagnetic material formed on the thin film layer of non-magnetic metallic material; at least one of the ferromagnetic layers being formed of cobalt or cobalt alloy and the magnetization direction of one of the layers of ferromagnetic material being substantially perpendicular to the magnetization direction of the other when no magnetic field is applied; means for producing a current flow through the magnetoresistive sensor; and means for sensing variations in the resistivity of the magnetic sensor caused by a difference in rotation of the magnetization directions in the layers of ferromagnetic material as a function of the magnetic field being sensed.
Claim 2
Dependent Claim
49 words
Magnetoresistive sensing apparatus as claimed in claim 1 wherein the magnetoresistive sensor further comprises: means for fixing the magnetization direction of the second layer of ferromagnetic material, whereby changes in resistivity are produced as a result of rotation of the magnetization direction in the first layer of ferromagnetic material.
Claim 3
Dependent Claim
46 words
Magnetoresistive sensing apparatus as claimed in claim 2 wherein the means for fixing the magnetization direction of the second layer of ferromagnetic material comprises providing the second layer of ferromagnetic material with a substantially higher coercivity than the coercivity of the first layer of ferromagnetic material.
Claim 4
Dependent Claim
43 words
Magnetoresistive sensing apparatus as claimed in claim 2 wherein the means for fixing the magnetization direction of the second layer of ferromagnetic material comprises a thin film layer of an exchange biasing material in direct contact with the second layer of ferromagnetic material.
Claim 5
Dependent Claim
32 words
Magnetoresistive sensing apparatus as claimed in any of the preceding claims wherein the layer of non-magnetic material is formed from a material taken from the group consisting of copper, silver and gold.
Claim 6
Dependent Claim
26 words
Magnetoresistive sensing apparatus as claimed in any of the preceding claims further comprising an underlayer disposed between the substrate and the first layer of ferromagnetic material.
Claim 7
Dependent Claim
25 words
Magnetoresistive sensing apparatus as claimed in claim 6 wherein the underlayer is formed of a material taken from the group consisting of tantalum and zirconium.
Claim 8
Dependent Claim
29 words
Magnetoresistive sensing apparatus as claimed in any of the preceding claims wherein the first ferromagnetic layer is NiFe and the second ferromagnetic layer is cobalt or a cobalt alloy.
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