MAGNETIC FIELD DETECTING DEVICE AND METHODS OF USING THE SAME

• US 20110211272A1
• Filed: 02/26/2010
• Published: 09/01/2011
• Est. Priority Date: 02/26/2010
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc), University of Alabama (University of Alabama System)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Butler, William Hill, Dimitrov, Dimitar V.
• Granted Patent: US 8,705,213 B2
• Time in Patent Office: Days
• US Class Current: 360/55
• CPC Class Codes: G11B 5/3912 Arrangements in which the active read-out elements are transducing in association with active magnetic shields, e.g. magnetically coupled shields G11B5/3916 takes precedence
• CPC Class Codes: G11B 5/398 Specially shaped layers
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A disclosed device having a principle axis and including a magnetoresistive stack, the magnetoresistive stack having first and second opposing surfaces, the magnetoresistive stack including a free layer, a spacer layer, and a reference layer, wherein the spacer layer is positioned between the first and reference layer, the free layer includes magnetic material having a free magnetic orientation in a first plane; the spacer layer includes a nonmagnetic material; and the reference layer includes a magnetic material having a pinned magnetic orientation in a second plane, wherein the second plane is perpendicular to the first plane and parallel to the principle axis of the device; an insulating layer at least a portion of the outer surface of the magnetoresistive stack; a shielding layer surrounding at least a portion of the insulating layer; and a conducting layer, wherein the conducting layer provides electrical connection between the magnetoresistive stack and the shielding layer.

Claims

1. A device having a principle axis, the device comprising:

a magnetoresistive stack, the magnetoresistive stack having first and second opposing surfaces,

the magnetoresistive stack comprising a free layer, a spacer layer, and a reference layer, wherein the spacer layer is positioned between the first and reference layer,

the free layer comprises magnetic material having a free magnetic orientation in a first plane;

the spacer layer comprises a nonmagnetic material; and

the reference layer comprises a magnetic material having a pinned magnetic orientation in a second plane,

wherein the second plane is perpendicular to the first plane and parallel to the principle axis of the device;

an insulating layer surrounding at least a portion of the outer surface of the magnetoresistive stack;

a shielding layer surrounding at least a portion of the insulating layer; and

a conducting layer, wherein the conducting layer provides electrical connection between the magnetoresistive stack and the shielding layer.

2. The device according to claim 1, wherein the spacer layer comprises a tunneling barrier material, a noble metal, a composite material comprising insulating material and conducting material, or TiN.

3. The device according to claim 1, wherein the free layer comprises cobalt (Co), iron (Fe), boron (B), nickel (Ni), copper (Cu), or alloys thereof.

4. The device according to claim 1, wherein the free layer comprises a top layer with in-plane magnetization and a bottom layer with an intrinsic anisotropy perpendicular to the bottom layer.

5. The device according to claim 4, wherein the top layer comprises cobalt (Co), iron (Fe), boron (B), nickel (Ni), copper (Cu), or alloys thereof;

and the bottom layer comprises FePt, CoPt, CoPd, Co/Cu multilayers, Co/Pt multilayers, Co/Pd multilayers, Fe/Pt multilayers, or Fe/Pd multilayers.

6. The device according to claim 1, wherein the reference layer comprises two exchange coupled layers.

7. The device according to claim 6, wherein the first exchange coupled layer comprises Co, CoFe, CoFeB, Ni, Fe, Co/Cu multilayers, or CoNiFe;

and the second exchange coupled layer comprises FePt, CoPt, CoPd, Co/Cu multilayers, Co/Pt multilayers, Co/Pd multilayers, Fe/Pt multilayers, or Fe/Pd multilayers.

8. The device according to claim 1, wherein the insulating layer is from about 3 nanometers (nm) to about 5 nm thick.

9. The device according to claim 1, wherein the shielding layer is from about 0.2 to about 2 nm thick.

11. The device according to claim 1, wherein the conducting layer comprises a bi-layer of a conductive material and a diamond like overcoat or a conductive nonmetallic material.

12. The device according to claim 1 incorporated into a magnetic recording and writing head.

13. A method of using a device, the method comprising:

bringing a magnetic field detecting device in proximity to a magnetic field generating article,

wherein the magnetic field detecting device has a principle axis and comprises a magnetoresistive stack, the magnetoresistive stack having first and second opposing surfaces,

the magnetoresistive stack comprising a free layer, a spacer layer, and a reference layer, wherein the spacer layer is positioned between the first and reference layer,

the free layer comprises magnetic material having a free magnetic orientation in a first plane;

the spacer layer comprises a nonmagnetic material; and

the reference layer comprises a magnetic material having a pinned magnetic orientation in a second plane,

wherein the second plane is perpendicular to the first plane and parallel to the principle axis of the device;

an insulating layer surrounding at least a portion of the outer surface of the magnetoresistive stack;

a shielding layer surrounding at least a portion of the insulating layer; and

a conducting layer, wherein the conducting layer provides electrical connection between the magnetoresistive stack and the shielding layer;

directing a current through the magnetic field detecting device; and

measuring the resistance of the magnetic field detecting device.

14. The method according to claim 13, wherein the current is directed through the magnetic field detecting device from the reference layer of the magnetoresistive stack, to the spacer layer, to the free layer, to the conducting layer, then to the shielding layer.

15. The method according to claim 13, wherein the magnetic field generating article is magnetic recording media.

16. The method according to claim 15, wherein the resistance of the magnetic field detecting device indicates a value stored in the magnetic recording media.

17. A method of using a device, wherein the device has a principle axis and comprises

a magnetoresistive stack, the magnetoresistive stack having first and second opposing surfaces,

the magnetoresistive stack comprising a free layer, a spacer layer, and a reference layer, wherein the spacer layer is positioned between the first and reference layer,

the free layer comprises magnetic material having a free magnetization orientation in a first plane;

the spacer layer comprises a nonmagnetic material; and

the reference layer comprises a magnetic material having a pinned magnetization orientation in a second plane,

wherein the second plane is perpendicular to the first plane and parallel to the principle axis;

an insulating layer surrounding at least a portion of the outer surface of the magnetoresistive stack; and

a shielding layer surrounding at least a portion of the insulating layer,

the method comprising;

causing the magnetic orientation of the free layer to spin; and

monitoring the resistance across the magnetoresistive stack in order to detect a magnetic field external to the device.

18. The method according to claim 17, wherein the magnetic orientation of the free layer is caused to spin by using the spin momentum transfer from a DC biasing current of at least about 50 μ

Amps.

19. The method according to claim 17, wherein the magnetic orientation of the free layer is caused to spin by applying a DC biasing current and an AC current that has a frequency equal to the natural spin momentum transfer oscillation frequency of the spin in the free layer.

20. The method according to claim 17, wherein causing the magnetic orientation of the free layer to spin reduces noise from the magnetic field detecting device.

21. The method according to claim 19 further comprising filtering the AC current in order to monitor the resistance across the magnetoresistive stack.

22. A method of forming a device comprising the steps of:

forming at least a first electrical contact on a substrate;

forming a magnetoresistive stack on at least a portion of the first electrical contact;

etching the magnetoresistive stack layer to form the magnetoresistive stack forming an insulating layer surrounding at least a portion of the magnetoresistive stack; and

forming a shielding layer surrounding at least a portion of the insulating layer.

23. The method according to claim 22 further comprising forming a second contact on a substrate and electrically connecting the shielding layer to the second contact.

24. The method according to claim 23, wherein the step of electrically connecting the shielding layer to the second contact is accomplished by forming a conducting layer that covers at least a portion of the shielding layer and at least a portion of the second contact or a conductive material electrically connected thereto.