MAGNETIC MATERIALS HAVING SUPERPARAMAGNETIC PARTICLES

• US 20070224454A1
• Filed: 04/20/2007
• Published: 09/27/2007
• Est. Priority Date: 06/10/2003
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Sun, Shouheng, Abraham, David, Trouilloud, Philip, Ingvarsson, Snorri, Koch, Roger
• Granted Patent: US 8,901,685 B2
• Time in Patent Office: Days
• US Class Current: 428/827
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 1/0063 in a non-magnetic matrix, e.g. granular solids granular films H01F10/007
• CPC Class Codes: H01F 10/007 ultrathin or granular films H01F10/005 and H01F10/3227 take precedence; applying ultrathin or granular layers to substrates H01F41/301
• CPC Class Codes: H01F 10/324 Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
• CPC Class Codes: H01F 41/301 for applying ultrathin or granular layers ultrathin or granular layers H01F10/007
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

Magnetic materials and uses thereof are provided. In one aspect, a magnetic film is provided. The magnetic film comprises superparamagnetic particles on at least one surface thereof. The magnetic film may be patterned and may comprise a ferromagnetic material. The superparamagnetic particles may be coated with a non-magnetic polymer and/or embedded in a non-magnetic host material. The magnetic film may have increased damping and/or decreased coercivity.

Claims

1. A magnetic film comprising superparamagnetic particles on at least one surface thereof configured to affect damping of the magnetic film, one or more of the superparamagnetic particles comprising a nanoparticle.

2. The magnetic film of claim 1, wherein the magnetic film is patterned.

3. The magnetic film of claim 1, for use in high frequency applications.

4. The magnetic film of claim 1, comprising a ferromagnetic material.

5. The magnetic film of claim 1, having a thickness of between about 0.5 nanometers to about five nanometers.

6. The magnetic film of claim 1, having a thickness of between about five nanometers to about 200 nanometers.

7. The magnetic film of claim 1, wherein the nanoparticle comprises a transition metal.

8. The magnetic film of claim 7, wherein the transition metal is selected from the group consisting of cobalt, nickel, iron, platinum, alloys comprising at least one of the foregoing transition metals, and intermetallics comprising at least one of the foregoing transition metals.

9. The magnetic film of claim 1, wherein the nanoparticle has a diameter of between about three nanometers to about 12 nanometers.

10. The magnetic film of claim 1, wherein the nanoparticle is coated with a polymer.

11. The magnetic film of claim 10, wherein the polymer is non-magnetic.

12. The magnetic film of claim 1, having increased damping.

13. The magnetic film of claim 1, having decreased coercivity.

14. The magnetic film of claim 1, wherein the superparamagnetic particles form at least one superparamagnetic layer.

15. The magnetic film of claim 14, wherein the at least one superparamagnetic layer comprises superparamagnetic particles embedded in a non-magnetic host material.

16. The magnetic film of claim 15, wherein the non-magnetic host material is selected from the group consisting of a metal, an insulator material, a semiconductor material, and combinations comprising at least one of the foregoing host materials.

17. A magnetic switching device comprising two magnetic layers with a barrier layer therebetween, wherein at least one of the magnetic layers comprises a magnetic film comprising superparamagnetic particles on at least one surface thereof.

18. The magnetic switching device of claim 17, wherein the superparamagnetic particles are spatially separated from the magnetic film.

19. The magnetic switching device of claim 18, wherein the superparamagnetic particles are spatially separated from the magnetic film by about ten angstroms to about 100 angstroms.

20. A magnetic random access memory (MRAM) comprising:

a plurality of memory cells; and

a plurality of word lines and a plurality of bit lines operatively coupled to the memory cells for selectively accessing the memory cells, wherein at least one of the memory cells comprises a magnetic switching device including a magnetic film comprising superparamagnetic particles on at least one surface thereof.

21. The MRAM of claim 20, wherein the superparamagnetic particles form a superparamagnetic layer.

22. The MRAM of claim 20, wherein the superparamagnetic particles form a plurality of superparamagnetic layers.

23. A magnetic film comprising at least one superparamagnetic particle on at least one surface thereof, the at least one superparamagnetic particle having a diameter of about three nanometers to about 12 nanometers.

24. The magnetic film of claim 23, comprising a single superparamagnetic particle.

25. The magnetic film of claim 23, wherein the at least one superparamagnetic particle is coated with a non-magnetic polymer.

26. The magnetic film of claim 23, wherein the at least one superparamagnetic particle is embedded in a non-magnetic host material.

27. A magnetic film comprising at least one superparamagnetic particle embedded therein.

28. The magnetic film of claim 27, wherein the at least one superparamagnetic particle is coated with a non-magnetic polymer.

29. A memory cell for use in magnetic random access memory (MRAM) comprising a magnetic switching device including a magnetic film comprising superparamagnetic particles on at least one surface thereof.