Magnetic tunnel junction sensor with AP-coupled free layer

Claim 2

A magnetic tunnel junction (MTJ) sensor, comprising: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an antiparallel (AP)-coupled free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer.

Claim 3

The MTJ sensor as recited in claim 1 wherein the first sense layer comprises: a ferromagnetic first interface layer made of cobalt formed on the first tunnel barrier layer; a ferromagnetic second interface layer made of cobalt; and a ferromagnetic layer made of Ni—Fe disposed between the first interface layer and the second interface layer.

Claim 4

The MTJ sensor as recited in claim 2 wherein the first interface layer has a thickness of about 5 Å.

Claim 5

The MTJ sensor as recited in claim 2 wherein the second interface layer has a thickness of about 5 Å.

Claim 6

The MTJ sensor as recited in claim 2 wherein said ferromagnetic layer made of Ni—Fe has a thickness in the range of 20-30 Å.

Claim 7

The MTJ sensor as recited in claim 1 wherein the second sense layer comprises: a ferromagnetic first interface layer made of cobalt formed on the APC layer; a ferromagnetic second interface layer made of cobalt; and a ferromagnetic layer made of Ni—Fe disposed between the first interface layer and the second interface layer.

Claim 8

The MTJ sensor as recited in claim 6 wherein the first interface layer has a thickness of about 5 Å.

Claim 9

The MTJ sensor as recited in claim 6 wherein the second interface layer has a thickness of about 5 Å.

Claim 10

The MTJ sensor as recited in claim 6 wherein said ferromagnetic layer made of Ni—Fe has a thickness in the range of 20-30 Å.

Claim 11

The MTJ sensor as recited in claim 1 wherein the APC layer is made of ruthenium.

Claim 12

The MTJ sensor as recited in claim 1 wherein the first sense layer is made of Ni—Fe.

Claim 13

The MTJ sensor as recited in claim 11 wherein the first sense layer has a thickness in the range of 20-40 Å.

Claim 14

The MTJ sensor as recited in claim 1 wherein the second sense layer is made of Ni—Fe.

Claim 15

The MTJ sensor as recited in claim 13 wherein the second sense layer has a thickness in the range of 20-40 Å.

Claim 16

The MTJ sensor as recited in claim 1 wherein the first and second tunnel barrier layers are made of Al 2 O 3 .

Claim 17

The MTJ sensor as recited in claim 1 wherein the AFM1 and AFM2 layers are made of Ir—Mn.

Claim 18

The MTJ sensor as recited in claim 1 wherein the AFM1 and AFM2 layers are selected from a group of materials consisting of Ir—Mn, Pt—Mn, Pt—Pd—Mn, and Ni—Mn.

Claim 19

The MTJ sensor as recited in claim 1 wherein the AFM1and AFM2 layers each have a thickness of about 60 Å.

Claim 20

The MTJ sensor as recited in claim 1 wherein the first and the second ferromagnetic pinned layers are made of Ni—Fe.

Claim 21

The MTJ sensor as recited in claim 1 wherein the first and second ferromagnetic pinned layers comprise a sublayer of NiFe and an interface layer of Co in contact with the tunnel barrier layers.

Claim 22

The MTJ sensor as recited in claim 1 wherein the magnetization direction of the first pinned layer in the first MTJ stack is parallel to the magnetization direction of the second pinned layer in the second MTJ stack.

Claim 23

A magnetic tunnel junction (MTJ) sensor, comprising: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an antiparallel (AP)-coupled free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and said AP-coupled free layer having a back edge electrically connected to a common electrode in a back region of the MTJ sensor; a first shield in contact with said first MTJ stack for providing a first sense current to said first MTJ stack; and a second shield in contact with said second MTJ stack for providing a second sense current to said second MTJ stack.

Claim 24

A magnetic tunnel junction (MTJ) sensor, comprising: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an antiparallel (AP)-coupled free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and said AP-coupled free layer having a back edge electrically connected to a common electrode in a back region of the MTJ sensor; a first shield in contact with said first MTJ stack for providing a first sense current to said first MTJ stack; and a second shield in contact with said second MTJ stack for providing a second sense current to said second MTJ stack.

Claim 25

The MTJ sensor as recited in claim 22 wherein the common electrode is made of gold.

Claim 26

The MTJ sensor as recited in claim 22 wherein the magnetization direction of the first pinned layer in the first MTJ stack is parallel to the magnetization direction of the second pinned layer in the second MTJ stack.

Claim 27

A magnetic read/write head, comprising: a write head including: at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack; first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS); the insulation stack being sandwiched between the first and second pole piece layers; and a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS; a read head including: a magnetic tunnel junction (MTJ) sensor, first and second shield layers and a common electrode, the MTJ sensor being sandwiched between the first and second shield layers; the MTJ sensor including: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an antiparallel-coupled (AP) free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and a back edge of said AP-coupled free layer connected to the common electrode; and an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head.

Claim 28

A magnetic read/write head, comprising: a write head including: at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack; first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS); the insulation stack being sandwiched between the first and second pole piece layers; and a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS; a read head including: a magnetic tunnel junction (MTJ) sensor, first and second shield layers and a common electrode, the MTJ sensor being sandwiched between the first and second shield layers; the MTJ sensor including: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an antiparallel-coupled (AP) free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and a back edge of said AP-coupled free layer connected to the common electrode; and an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head.

Claim 29

The magnetic read/write head as recited in claim 25 wherein the first sense layer comprises: a ferromagnetic first interface layer made of cobalt formed on the first tunnel barrier layer; a ferromagnetic second interface layer made of cobalt; and a ferromagnetic layer made of Ni—Fe disposed between the first interface layer and the second interface layer.

Claim 30

The magnetic read/write head as recited in claim 26 wherein the first interface layer has a thickness of about 5 Å.

Claim 31

The magnetic read/write head as recited in claim 26 wherein the second interface layer has a thickness of about 5 Å.

Claim 32

The magnetic read/write head as recited in claim 26 wherein said ferromagnetic layer made of Ni—Fe has a thickness in the range of 20-30 Å.

Claim 33

The magnetic read/write head as recited in claim 25 wherein the second sense layer comprises: a ferromagnetic first interface layer made of cobalt formed on the APC layer; a ferromagnetic second interface layer made of cobalt; and a ferromagnetic layer made of Ni—Fe disposed between the first interface layer and the second interface layer.

Claim 34

The magnetic read/write head as recited in claim 30 wherein the first interface layer has a thickness of about 5 Å.

Claim 35

The magnetic read/write head as recited in claim 30 wherein the second interface layer has a thickness of about 5 Å.

Claim 36

The magnetic read/write head as recited in claim 30 wherein said ferromagnetic layer made of Ni—Fe has a thickness in the range of 20-30 Å.

Claim 37

The magnetic read/write head as recited in claim 25 wherein the APC layer is made of ruthenium.

Claim 38

The magnetic read/write head as recited in claim 25 wherein the first sense layer is made of Ni—Fe.

Claim 39

The magnetic read/write head as recited in claim 35 wherein the first sense layer has a thickness in the range of 20-40 Å.

Claim 40

The magnetic read/write head as recited in claim 25 wherein the second sense layer is made of Ni—Fe.

Claim 41

The magnetic read/write head as recited in claim 37 wherein the second sense layer has a thickness in the range of 20-40 Å.

Claim 42

The magnetic read/write head as recited in claim 25 wherein the first and second tunnel barrier layers are made of Al 2 O 3 .

Claim 43

The magnetic read/write head as recited in claim 25 wherein the AFM1 and AFM2 layers are made of Ir—Mn.

Claim 44

The magnetic read/write head as recited in claim 25 wherein the AFM1 and AFM2 layers are selected from a group of materials consisting of Ir—Mn, Pt—Mn, Pt—Pd—Mn and Ni—Mn.

Claim 45

The magnetic read/write head as recited in claim 25 wherein the AFM1 and AFM2 layers each have a thickness of about 60 Å.

Claim 46

The magnetic read/write head as recited in claim 25 wherein the first and the second ferromagnetic pinned layers are made of Ni—Fe.

Claim 47

The magnetic read/write head as recited in claim 25 wherein the first and second ferromagnetic pinned layers comprise a sublayer of Ni—Fe and an interface layer of Co in contact with the tunnel barrier layers.

Claim 48

A disk drive system comprising: a magnetic recording disk; a magnetic read/write head for magnetically recording data on the magnetic recording disk and for sensing magnetically recorded data on the magnetic recording disk, said magnetic read/write head comprising: a write head including: at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack; first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS); the insulation stack being sandwiched between the first and second pole piece layers; and a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS; a read head including: a magnetic tunnel junction (MTJ) sensor, first and second shield layers and a common electrode, the MTJ sensor being sandwiched between the first and second shield layers; the MTJ sensor including: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an AP-coupled free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and a back edge of said AP-coupled free layer connected to the common electrode; and an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head; an actuator for moving said magnetic read/write head across the magnetic disk so that the read/write head may access different regions of the magnetic recording disk; and a recording channel coupled electrically to the write head for magnetically recording data on the magnetic recording disk and to the MTJ sensor of the read head for detecting changes in resistance of the MTJ sensor caused by rotation of the magnetization axis of the AP-coupled free layer relative to the fixed magnetizations of the first and second pinned layers in response to magnetic fields from the magnetically recorded data.

Claim 49

A disk drive system comprising: a magnetic recording disk; a magnetic read/write head for magnetically recording data on the magnetic recording disk and for sensing magnetically recorded data on the magnetic recording disk, said magnetic read/write head comprising: a write head including: at least one coil layer and an insulation stack, the coil layer being embedded in the insulation stack; first and second pole piece layers connected at a back gap and having pole tips with edges forming a portion of an air bearing surface (ABS); the insulation stack being sandwiched between the first and second pole piece layers; and a write gap layer sandwiched between the pole tips of the first and second pole piece layers and forming a portion of the ABS; a read head including: a magnetic tunnel junction (MTJ) sensor, first and second shield layers and a common electrode, the MTJ sensor being sandwiched between the first and second shield layers; the MTJ sensor including: a first MTJ stack, comprising: a first antiferromagnetic (AFM1) layer; a first tunnel barrier layer; and a first ferromagnetic pinned layer disposed between the AFM1 layer and the first tunnel barrier layer; a second MTJ stack, comprising: a second antiferromagnetic (AFM2) layer; a second tunnel barrier layer; and a second ferromagnetic pinned layer disposed between the AFM2 layer and the second tunnel barrier layer; and an AP-coupled free layer disposed between the first tunnel barrier layer and the second tunnel barrier layer, said AP-coupled free layer comprising a ferromagnetic first sense layer adjacent to and in contact with the first tunnel barrier layer, a ferromagnetic second sense layer adjacent to and in contact with the second tunnel barrier layer, and an antiparallel coupling (APC) layer disposed between the first sense layer and the second sense layer; and a back edge of said AP-coupled free layer connected to the common electrode; and an insulation layer disposed between the second shield layer of the read head and the first pole piece layer of the write head; an actuator for moving said magnetic read/write head across the magnetic disk so that the read/write head may access different regions of the magnetic recording disk; and a recording channel coupled electrically to the write head for magnetically recording data on the magnetic recording disk and to the MTJ sensor of the read head for detecting changes in resistance of the MTJ sensor caused by rotation of the magnetization axis of the AP-coupled free layer relative to the fixed magnetizations of the first and second pinned layers in response to magnetic fields from the magnetically recorded data.