Tunnel junction head structure without current shunting

Claim 2

A magnetic tunnel junction (MTJ) sensor, comprising: a substrate; a first shield (S1) of ferromagnetic material formed on the substrate; a magnetic tunnel junction (MTJ) stack formed on said first shield, the MTJ stack having a generally rectangular shape and two opposite side edges, said MTJ stack comprising: an antiferromagnetic (AFM) layer; a pinned layer of ferromagnetic material in contact with said AFM layer; a free layer of ferromagnetic material; and a tunnel junction layer of electrically insulating material disposed between said pinned layer and said free layer; a second shield (S2) of ferromagnetic material formed on and in contact with said MTJ stack; a first insulator layer formed on the first shield layer on opposite sides of said MTJ stack and in abutting contact to the side edges of said MTJ stack; a hard bias layer of ferromagnetic material formed on the first insulator layer on opposite sides of said MTJ stack and in abutting contact to or overlapping said MTJ stack, said hard bias layer having a magnetic moment for biasing the magnetic moment of the free layer in substantially the same direction as the moment of the hard bias layer in the absence of an applied magnetic field; and a second insulator layer formed on the hard bias layer and separating said hard bias layer from said second shield layer.

Claim 3

The MTJ sensor as recited in claim 1, wherein the thickness of said first insulator layer is substantially equal to the thickness of said MTJ stack.

Claim 4

The MTJ sensor as recited in claim 1, wherein said first insulator layer is made of Al 2 O 3 .

Claim 5

The MTJ sensor as recited in claim 1, wherein said second insulator layer is made of Al 2 O 3 .

Claim 6

The MTJ sensor as recited in claim 1, further comprising: a first electrical connection fixed on said first shield for making electrical contact from said first shield to a current source and to a signal detector; and a second electrical connection fixed on said second shield for making electrical contact from said second shield to said current source and to said signal detector; said first and second shields providing electrical leads for sensing the electrical resistance to sense current flow perpendicularly through the MTJ stack and sense current flow is prevented by said first insulator layer from shunting around said MTJ stack.

Claim 7

The MTJ sensor as recited in claim 1, wherein said hard bias layer is made of Co--Pt--Cr.

Claim 8

The MTJ sensor as recited in claim 1, wherein said AFM layer is made of Mn 50 --Fe 50 .

Claim 9

The MTJ sensor as recited in claim 1, wherein said AFM layer is chosen from a group of materials including Mn--Fe, Ni--Mn, Pd--Mn, Pt--Mn, Pd--Pt--Mn, Ir--Mn, Rh--Mn, and Cr--Mn--Pt.

Claim 10

The MTJ sensor as recited in claim 1, wherein said first shield is made from Ni--Fe.

Claim 11

The MTJ sensor as recited in claim 1, wherein said second shield is made from Ni--Fe.

Claim 12

A disk drive system comprising: a magnetic recording disk; a magnetic tunnel junction (MTJ) sensor for sensing magnetically recorded data on said magnetic recording disk, said MTJ sensor comprising: a substrate; a first shield (S1) of ferromagnetic material formed on the substrate; a magnetic tunnel junction (MTJ) stack formed on said first shield, the MTJ stack having a generally rectangular shape and two opposite side edges, said MTJ stack comprising: an antiferromagnetic (AFM) layer; a pinned layer of ferromagnetic material in contact with said AFM layer; a free layer of ferromagnetic material; and a tunnel junction layer of electrically insulating material disposed between said pinned layer and said free layer; a second shield (S2) of ferromagnetic material formed on and in contact with said MTJ stack; a first insulator layer formed on the first shield layer on opposite sides of said MTJ stack and in abutting contact to the side edges of said MTJ stack; a hard bias layer of ferromagnetic material formed on the first insulator layer on opposite sides of said MTJ stack and in abutting contact to or overlapping said MTJ stack, said hard bias layer having a magnetic moment for biasing the magnetic moment of the free layer in substantially the same direction as the moment of the hard bias layer in the absence of an applied magnetic field; and a second insulator layer formed on the hard bias layer and separating said hard bias layer from said second shield layer; an actuator for moving said MTJ sensor across the magnetic recording disk so the MTJ sensor may access different regions of magnetically recorded data on the magnetic recording disk; and a recording channel coupled electrically to the MTJ sensor for detecting changes in resistance of the MTJ sensor caused by rotation of the magnetization axis of the free ferromagnetic layer relative to the fixed magnetization of the pinned layer in response to magnetic fields from the magnetically recorded data.

Claim 13

A disk drive system comprising: a magnetic recording disk; a magnetic tunnel junction (MTJ) sensor for sensing magnetically recorded data on said magnetic recording disk, said MTJ sensor comprising: a substrate; a first shield (S1) of ferromagnetic material formed on the substrate; a magnetic tunnel junction (MTJ) stack formed on said first shield, the MTJ stack having a generally rectangular shape and two opposite side edges, said MTJ stack comprising: an antiferromagnetic (AFM) layer; a pinned layer of ferromagnetic material in contact with said AFM layer; a free layer of ferromagnetic material; and a tunnel junction layer of electrically insulating material disposed between said pinned layer and said free layer; a second shield (S2) of ferromagnetic material formed on and in contact with said MTJ stack; a first insulator layer formed on the first shield layer on opposite sides of said MTJ stack and in abutting contact to the side edges of said MTJ stack; a hard bias layer of ferromagnetic material formed on the first insulator layer on opposite sides of said MTJ stack and in abutting contact to or overlapping said MTJ stack, said hard bias layer having a magnetic moment for biasing the magnetic moment of the free layer in substantially the same direction as the moment of the hard bias layer in the absence of an applied magnetic field; and a second insulator layer formed on the hard bias layer and separating said hard bias layer from said second shield layer; an actuator for moving said MTJ sensor across the magnetic recording disk so the MTJ sensor may access different regions of magnetically recorded data on the magnetic recording disk; and a recording channel coupled electrically to the MTJ sensor for detecting changes in resistance of the MTJ sensor caused by rotation of the magnetization axis of the free ferromagnetic layer relative to the fixed magnetization of the pinned layer in response to magnetic fields from the magnetically recorded data.

Claim 14

The disk drive system as recited in claim 11, wherein the thickness of said first insulator layer is substantially equal to the thickness of said MTJ stack.

Claim 15

The disk drive system as recited in claim 11, wherein said first insulator layer is made of Al 2 O 3 .

Claim 16

The disk drive system as recited in claim 11, wherein said second insulator layer is made of Al 2 O 3 .

Claim 17

The disk drive system as recited in claim 11, further comprising: a first electrical connection fixed on said first shield for making electrical contact from said first shield to a current source and to a signal detector; and a second electrical connection fixed on said second shield for making electrical contact from said second shield to said current source and to said signal detector; said first and second shields providing electrical leads for sensing the electrical resistance to sense current flow perpendicularly through the MTJ stack and sense current flow is prevented by said first insulator layer from shunting around said MTJ stack.

Claim 18

The disk drive system as recited in claim 11, wherein said hard bias layer is made of Co--Pt--Cr.

Claim 19

The disk drive system as recited in claim 11, wherein said AFM layer is made of Mn 50 --Fe 50 .

Claim 20

The disk drive system as recited in claim 11, wherein said AFM layer is chosen from a group of materials including Mn--Fe, Ni--Mn, Pd--Mn, Pt--Mn, Pd--Pt--Mn, Ir--Mn, Rh--Mn, and Cr--Mn--Pt.

Claim 21

The disk drive system as recited in claim 11, wherein said first shield is made from Ni--Fe.

Claim 22

The disk drive system as recited in claim 11, wherein said second shield is made from Ni--Fe.