Giant magnetoresistive effect sensor, particularly having a multilayered magnetic thin film layer

Claim 2

A magnetoresistive spin-valve sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic metallic material sandwiched between said first and second magnetic thin film layers; a thin film layer of anti-ferromagnetic material adjacent to said second magnetic thin film layer and in exchange coupling at adjacent surfaces with said second magnetic thin film layer to fix a magnetization orientation of said second magnetic thin film layer along a substantially fixed first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer, said thin film layer of anti-ferromagnetic material and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 3

A magnetoresistive sensor according to claim 1, wherein each of said magnetic thinner film layers is composed of an alloy including each of Fe, Ni and Co.

Claim 4

A magnetoresistive sensor according to claim 2, wherein said alloy has Co and Fe in a weight ratio of 90:10.

Claim 5

A magnetoresistive sensor according to claim 3, wherein said alloy is more than 50% by weight Co, and the remainder Fe and Ni.

Claim 6

A magnetoresistive sensor according to claim 1, wherein said first magnetic thin film layer and said second magnetic thin film layer have magnetization directions parallel to each other.

Claim 7

A magnetoresistive sensor according to claim 1, wherein said crystal structure is a face centered cubic structure.

Claim 8

A magnetoresistive sensor according to claim 1, wherein said crystal orientation is an orientation of a crystal plane (111) substantially parallel to all of said thin film layers.

Claim 9

A magnetoresistive sensor according to claim 1, wherein each magnetic thinner film layer in said first magnetic thin film layer has a thickness of 30 angstroms or less.

Claim 10

A magnetoresistive sensor according to claim 1, wherein: said first magnetic thin film layer has said magnetic thinner film layers separated from each other and sandwiching therebetween said interlayers that cut single-crystal grain epitaxial growth between said magnetic thinner film layers; and said interlayers have the same crystal structure and crystal plane orientation as said magnetic thinner film layers.

Claim 11

A magnetoresistive sensor according to claim 9, wherein said interlayers include elemental Cu or a Cu alloy.

Claim 12

A magnetoresistive sensor according to claim 9, wherein said interlayers include elemental Ni or a Ni alloy.

Claim 13

A magnetoresistive sensor according to claim 9, wherein each of said interlayers is less than 10 angstroms thick.

Claim 14

A magnetoresistive sensor according to claim 1, further including means providing a longitudinally extending magnetic field through all of said thin film layers in an amount sufficient to reduce Barkhausen noise.

Claim 15

A magnetoresistive sensor according to claim 1, wherein said first magnetic thin film layer as a whole has a magnetostriction that is less than 3×10 -6 .

Claim 16

A magnetoresistive sensor according to claim 1, wherein said first magnetic thin film layer as a whole has a magnetostriction that is less than 1×10 6 .

Claim 17

A magnetoresistive sensor according to claim 1, wherein said first magnetic thin film layer, said second magnetic thin film layer, said thin film layer of anti-ferromagnetic material and said non-magnetic thin film layer exhibit a magnetic orientation and annealed structure resulting from being annealed and cooled in a magnetic field sufficiently to have an anisotropic energy of said first magnetic thin film layer in an equilibrium state that is smaller than an identical structure before annealing.

Claim 18

A magnetoresistive sensor according to claim 1, further including an underlayer of one of Ta, Zr, Nb, Ti and Hf, and a substrate sandwiching said underlayer between said substrate and said first magnetic thin film layer.

Claim 19

A magnetoresistive sensor according to claim 1, further including first and second magnetic shields on respective faces of said thin film layer of anti-ferromagnetic material and said first magnetic thin film layer, which faces are opposite sides from said second magnetic thin film layer.

Claim 20

A magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic metallic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a fixed magnetization orientation along a substantially fixed first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 21

A magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic metallic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a fixed magnetization orientation along a substantially fixed first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 22

A magnetoresistive sensor according to claim 19, wherein each of said magnetic thinner film layers is composed of an alloy including each of Fe, Ni and Co.

Claim 23

A magnetoresistive sensor according to claim 20, wherein said alloy has Co and Fe in a weight ratio of 90:10.

Claim 24

A magnetoresistive sensor according to claim 19, wherein said crystal structure is a face centered cubic structure.

Claim 25

A magnetoresistive sensor according to claim 19, wherein said crystal orientation is an orientation of a crystal plane (111) substantially parallel to all of said thin film layers.

Claim 26

A magnetoresistive sensor according to claim 19, wherein each magnetic thinner film layer in said first magnetic thin film layer has a thickness of 30 angstroms or less.

Claim 27

A magnetoresistive sensor according to claim 19, wherein: said first magnetic thin film layer has said magnetic thinner film layers separated from each other and sandwiching therebetween said interlayers that cut single-crystal grain epitaxial growth between said magnetic thinner film layers; and said interlayers have the same crystal structure and crystal plane orientation as said magnetic thinner film layers.

Claim 28

A magnetoresistive sensor according to claim 19, wherein said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer exhibit a magnetic orientation and annealed structure resulting from being annealed and cooled in a magnetic field sufficiently to have an anisotropic energy of said first magnetic thin film layer in an equilibrium state that is smaller than an identical structure before annealing.

Claim 29

A magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic metallic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a magnetization orientation along a first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 30

A magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic metallic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a magnetization orientation along a first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 31

A magnetoresistive sensor according to claim 27, wherein each of said magnetic thinner film layers is composed of an alloy including each of Fe, Ni and Co.

Claim 32

A magnetoresistive sensor according to claim 28, wherein said alloy has Co and Fe in a weight ratio 90:10.

Claim 33

A magnetoresistive sensor according to claim 27, wherein said crystal structure is a face centered cubic structure.

Claim 34

A magnetoresistive sensor according to claim 27, wherein said crystal orientation is an orientation of a crystal plane (111) substantially parallel to all of said thin film layers.

Claim 35

A magnetoresistive sensor according to claim 27, wherein each magnetic thinner film layer in said first magnetic thin film layer has a thickness of 30 angstroms or less.

Claim 36

A magnetoresistive sensor according to claim 27, wherein: said first magnetic thin film layer has said magnetic thinner film layers separated from each other and sandwiching therebetween said interlayers that cut single-crystal grain epitaxial growth between said magnetic thinner film layers; and said interlayers have the same crystal structure and crystal plane orientation as said magnetic thinner film layers.

Claim 37

A magnetoresistive sensor according to claim 27, wherein said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer exhibit a magnetic orientation and annealed structure resulting from being annealed and cooled in a magnetic field sufficiently to have an anisotropic energy of said first magnetic thin film layer in an equilibrium state that is smaller than an identical structure before annealing.

Claim 38

A magnetoresistive sensor according to claim 27, wherein said second magnetic thin film layer has a permanent magnetic bias provided by an applied electric current.

Claim 39

A magnetoresistive sensor according to claim 27, wherein said second magnetic thin film layer has a permanent magnetic bias applied by a permanent magnet.

Claim 40

A magnetoresistive sensor according to claim 27, wherein said second magnetic thin film layer has a permanent magnetic bias supplied by said second thin film layer being a hard ferromagnetic material relative to said first thin film layer being a soft ferromagnetic material.

Claim 41

In a magnetic information data storage system, having: a magnetic storage medium having a plurality of tracks for recording data as separate magnetic domains along said tracks, and a magnetic transducer being maintained in a closely spaced position relative to said magnetic storage medium during relative movement between said magnetic transducer and said magnetic storage medium for transducing, said magnetic transducer including a magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a magnetization orientation along a first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 42

In a magnetic information data storage system, having: a magnetic storage medium having a plurality of tracks for recording data as separate magnetic domains along said tracks, and a magnetic transducer being maintained in a closely spaced position relative to said magnetic storage medium during relative movement between said magnetic transducer and said magnetic storage medium for transducing, said magnetic transducer including a magnetoresistive sensor of the giant magnetoresistive type, comprising: a first magnetic thin film layer of substantially ferromagnetic material; a second magnetic thin film layer of substantially ferromagnetic material; a non-magnetic thin film layer of non-magnetic material sandwiched between said first and second magnetic thin film layers; said second magnetic thin film layer having a magnetization orientation along a first direction; said first magnetic thin film layer having a magnetization orientation that is in a second direction that is freely movable relative to said first direction in response to externally applied magnetic fields to be sensed, for thereby changing resistance of the layers to a passage of an electric sensing current in proportion to a first power of cosine of an angle θ between said first direction and said second direction; said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer each having a same crystal structure and a same crystal plane orientation; and said first magnetic thin film layer comprising a plurality of magnetic thinner film layers of ferromagnetic material with the same crystal plane orientation from one of said magnetic thinner films to another, and an interlayer between each adjacent ones of said magnetic thinner film layers providing a discontinuity in single-crystal epitaxial growth between each of said magnetic thinner film layers.

Claim 43

A magnetic information data storage system according to claim 38, wherein a magnetic easy axis for each of said first and second magnetic thin film layers is substantially perpendicular to a track width of said tracks.

Claim 44

A magnetic information data storage system according to claim 38, further including: a motor connected between said magnetic storage medium and said magnetoresistive sensor for relatively moving said magnetoresistive sensor along said tracks; a separate motor connected between said magnetic storage medium and said magnetoresistive sensor for moving said magnetic storage medium and magnetoresistive sensor relative to each other in a direction generally perpendicular to said tracks for accessing; and a control circuit controlling speed and operation of said motors.

Claim 45

A magnetic information data storage system according to claim 38, wherein said interlayers are composed of magnetic materials.

Claim 46

A magnetic information data storage system according to claim 38, wherein said interlayers are composed of non-magnetic materials.

Claim 47

A magnetic information data storage system according to claim 38, wherein crystal growth is discontinuous between said thinner film layers so that average crystal grain size of said first thin film layer is substantially less than average crystal grain size of a thin film layer identical in all respects except for being composed of only a single-crystal epitaxial layer, in a plane of said first thin film layer.

Claim 48

A magnetic information data storage system according to claim 38, wherein said magnetic thinner film layers have matched exchange couplings between layers.

Claim 49

A magnetic information data storage system according to claim 38, wherein each of said magnetic thinner film layers has an identical material composition.

Claim 50

A magnetic information data storage system according to claim 38, wherein each of said magnetic thinner film layers is composed of a alloy including each of Fe, Ni and Co.

Claim 51

A magnetic information data storage system according to claim 46, wherein said alloy preferably has a Co composition of greater than 50% by weight.

Claim 52

A magnetic information data storage system according to claim 46, wherein said alloy has Co and Fe in a weight ratio of 90:10.

Claim 53

A magnetic information data storage system according to claim 46, wherein said alloy includes Ni in an amount between 30 and 53% by weight.

Claim 54

A magnetic information data storage system according to claim 38, wherein said crystal structure is a face centered cubic structure.

Claim 55

A magnetic information data storage system according to claim 38, wherein said crystal orientation is an orientation of a crystal plane (111) substantially parallel to all of said thin film layers.

Claim 56

A magnetic information data storage system according to claim 38, wherein each magnetic thinner film layer in said first magnetic thin film layer has a thickness of 30 angstroms or less.

Claim 57

A magnetic information data storage system according to claim 38, wherein: said first magnetic thin film layer has said magnetic thinner film layers separated from each other and sandwiching therebetween said interlayers that cut single-crystal grain growth between said magnetic thinner film layers; and said interlayers have the same crystal structure and crystal plane orientation as said magnetic thinner film layers.

Claim 58

A magnetic information data storage system according to claim 38, wherein said first magnetic thin film layer, said second magnetic thin film layer and said non-magnetic thin film layer exhibit magnetic orientation and annealed structure resulting from being annealed and cooled in a magnetic field sufficiently to have an anisotropic energy of said first magnetic thin film layer in an equilibrium state that is smaller than an identical structure before annealing.

Claim 59

A magnetic information data storage system according to claim 38, wherein said magnetoresistive sensor further includes a thin film layer of anti-ferromagnetic material adjacent to said second magnetic thin film layer and in exchange coupling at adjacent surfaces with said second magnetic thin film layer to fix a magnetization orientation of said second magnetic thin film layer along a substantially fixed first direction.

Claim 60

A magnetic information data storage system according to claim 38, wherein said magnetoresistive sensor further includes means fixing said first direction.