Magnetoresistive read transducer having hard magnetic shunt bias

Claim 2

A magnetoresistive read transducer comprising: a thin film of magnetoresistive conductive layer (11) formed of magnetic material, said magnetoresistive conductive layer having passive end regions (14) separated by a central active region (12); and means for producing a longitudinal magnetostatic bias in the passive end regions of said magnetoresistive layer, said means for producing a longitudinal bias com­prising a thin film (16) of hard magnetic material parallel to, but spaced from, said magnetoresistive layer in the passive end regions only whereby said longitudinal bias maintains said active region of said magnetoresistive layer in a single domain state.

Claim 3

The magnetoresistive read transducer of claim 1, wherein said thin film of hard magnetic material com­prises a cobalt alloy.

Claim 4

The magnetoresistive read transducer of claim 2, wherein said thin film of hard magnetic material is a cobalt platinum chromium alloy.

Claim 5

The magnetoresistive read transducer of claim 1, wherein the spacing of said thin film of hard magnetic material is maintained by a nonmagnetic electrically con­ductive spacer layer between said thin film of hard magnetic material and said magnetoresistive layer.

Claim 6

The magnetoresistive read transducer of claim 4, wherein said nonmagnetic spacer layer has a thickness within the range of 500-2000 angstroms.

Claim 7

A magnetoresistive read transducer comprising: a thin film of magnetoresistive conductive layer formed of magnetic material, said magnetoresistive conduct­ive layer having passive end regions separated by a central active region; means for producing a transverse bias in said central active region of said magnetoresistive layer of a level sufficient to maintain said central region of said magnetoresistive layer in a linear response mode; means for producing a longitudinal bias in the passive end regions of said magnetoresistive layer, said means for producing a longitudinal bias comprising a thin film of hard magnetic materials parallel to, but spaced from, said magnetoresistive layer in the passive end regions only whereby said longitudinal bias maintains said passive end regions of said magnetoresistive layer in a stable reversed state; and spaced conductor means coupled to said magneto­resistive layer to define a detection region whereby sensing means connected to said conductor means can determine the resistance changes in the central active region of said magnetoresistive layer as a function of the fields which are intercepted by said magnetoresistive layer.

Claim 8

A magnetoresistive read transducer comprising: a thin film of magnetoresistive conductive layer formed of magnetic material, said magnetoresistive conduct­ive layer having passive end regions separated by a central active region; means for producing a transverse bias in said central active region of said magnetoresistive layer of a level sufficient to maintain said central region of said magnetoresistive layer in a linear response mode; means for producing a longitudinal bias in the passive end regions of said magnetoresistive layer, said means for producing a longitudinal bias comprising a thin film of hard magnetic materials parallel to, but spaced from, said magnetoresistive layer in the passive end regions only whereby said longitudinal bias maintains said passive end regions of said magnetoresistive layer in a stable reversed state; and spaced conductor means coupled to said magneto­resistive layer to define a detection region whereby sensing means connected to said conductor means can determine the resistance changes in the central active region of said magnetoresistive layer as a function of the fields which are intercepted by said magnetoresistive layer.

Claim 9

The magnetoresistive read transducer of claim 6, wherein said thin film of hard magnetic material com­prises a cobalt alloy.

Claim 10

The magnetoresistive read transducer of claim 7, wherein said thin film of hard magnetic material is a cobalt platinum chromium alloy.

Claim 11

The magnetoresistive read transducer of claim 6, wherein the spacing of said thin film of hard magnetic material from said magnetoresistive layer is maintained by a nonmagnetic spacer layer between said thin film of hard magnetic material and said magnetoresistive layer.

Claim 12

The magnetoresistive read transducer of claim 9, wherein said nonmagnetic spacer layer has a thickness within the range of 500-2000 angstroms.

Claim 13

The magnetoresistive read transducer of claim 9, wherein said nonmagnetic spacer layer is a dual function layer which also serves as said spaced conductor means.

Claim 14

The magnetoresistive read transducer of claim 6 wherein said magnetic flux produced by said longitudinal bias in said end regions exceeds the longitudinal component of flux in said central region.

Claim 15

The magnetoresistive read transducer of claim 12 wherein the ratio of longitudinal flux in said end regions to said longitudinal component of flux in said central region is in the range of 1 to 2.

Claim 16

The magnetoresistive read transducer of claim 6 wherein said means for producing a transverse bias in said central region of said magnetoresistive layer comprises a soft magnetic layer spaced from said magnetoresistive layer, said soft magnetic layer extending over both said end regions and said central region of said magnetoresistive layer.

Claim 17

The magnetoresistive read transducer of claim 14 wherein the magnetization produced by said means for producing a longitudinal bias is chosen of a level so that the magnetization state in the end regions of said magneto­resistive layer and said soft magnetic layer are of the same direction but both being opposite to the magnetization direction in the active region of the magnetoresistive layer in the unbiased state.