MULTI-STATE MEMORY AND MULTI-FUNCTIONAL DEVICES COMPRISING MAGNETOPLASTIC OR MAGNETOELASTIC MATERIALS

• US 20110110139A1
• Filed: 05/04/2010
• Published: 05/12/2011
• Est. Priority Date: 11/14/2006
• Status: Active Grant

• Current Assignee: Boise State University
• Original Assignee: Boise State University
• Inventors: KNOWLTON, WILLIAM B., MULLNER, PETER
• Granted Patent: US 8,233,314 B2
• Time in Patent Office: Days
• US Class Current: 365/129
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: G11C 11/5607 using magnetic storage elements
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 35/85 Magnetostrictive active materials
• CPC Class Codes: Y10T 29/49764 with testing or indicating

Abstract

Apparatus and methods are disclosed that enable writing data on, and reading data of, multi-state elements having greater than two states. The elements may be made of magnetoplastic and/or magnetoelastic materials, including, for example, magnetic shape-memory alloy or other materials that couple magnetic and crystallographic states. The writing process is preferably conducted through the application of a magnetic field and/or a mechanical action. The reading process is preferably conducted through atomic-force microscopy, magnetic-force microscopy, spin-polarized electrons, magneto-optical Kerr effect, optical interferometry or other methods, or other methods/effects. The multifunctionality (crystallographic, magnetic, and shape states each representing a functionality) of the multi-state elements allows for simultaneous operations including read&write, sense&indicate, and sense&control. Embodiments of the invention may be used, for example, for storing, modifying, and accessing data for device, sensor, actuator, logic and memory applications. Embodiments may be particularly effective for non-volatile memory or other read&write, sense&indicate, and/or sense&control functions in computer or other applications; such simultaneous operation of two (or more) of said multiple functionalities open new pathways for miniaturization of devices.

Claims

1. A logic or memory device comprising a magnetoplastic and/or magnetoelastic material having at least six states selected from the group consisting of magnetic states, crystallographic states, and shape states.

2. A device as in claim 1 which is a combined logic and memory device.

3. A device as in claim 2 wherein the memory is nonvolatile.

4. A device as in claim 1, wherein said material is magnetic shape memory alloy.

5. A device as in claim 1, wherein said material is selected from the group consisting of:

Heusler shape-memory alloy, non-Heusler ferromagnetic shape-memory alloy, antiferromagnetic shape-memory alloy, non-shape-memory magnetoplastic alloy, Ni₂MnGa, Dy, α

-Fe, Co—

Ni, τ

-MnAl—

C, L1₀ FePd, L1₀ CoPt, L1₀ FePt, Ni₂MnGa, Co₂NiGa, Ni₂MnAl, Ni₂FeGa, Fe₃Pd, Fe—

Pd—

PT, γ

-Mn—

Fe—

Cu, Ni₅₁Mn₂₈Ga₂₁, Ni—

Mn—

Ga alloys, Ni—

Mn—

Ga ferromagnetic martensite, and combinations thereof.

6. A device as in claim 1 that is a data reading and writing device.

7. A device as in claim 1 that is a displacement and sensing device.

8. A device as in claim 1 that is a sensing and control device.

9. A device as in claim 1 that is a sensing and indicating device.

10. A device as in claim 1, wherein two of said at least six states are read and write operators.

11. A device as in claim 1, wherein two of said at least six states are sense and indicate operators.

12. A device as in claim 1, wherein two of said at least six states are sense and control operators.

13. A sensor, actuator, logic or memory device comprising a non-cubic crystal having multiple crystallographic states, and wherein said device comprises means for controlling, and means for detecting, said multiple crystallographic states.

14. A device as in claim 13 wherein said crystallographic states are related to magnetic states.

15. A device as in claim 13 wherein said crystallographic states are related to shape states.

16. A device as in claim 13 wherein said means for controlling is a magnetic field.

17. A device as in claim 13 wherein said means for controlling is a mechanical force.

18. A device as in claim 13 wherein said means for controlling is an A/C electric field.

19. A device as in claim 13, wherein said crystal is a magnetic shape-memory alloy.

20. A device as in claim 13 wherein said crystal is magnetically and crystallographically anisotropic and the magnetic and crystallographic anisotropy are coupled.

21. A device as in claim 13 wherein said means for detecting comprises detection using the magneto-optical Kerr effect.

22. A device as in claim 13, wherein said means for detecting comprises detection with spin-polarized electrons.

23. A device as in claim 13, wherein said means for detecting comprises detection with optical interferometry.

25. A device as in claim 13, wherein said crystal is attached to or grown on a substrate.

26. A logic or memory device comprising a magnetoplastic and/or magnetoelastic material having at least six states selected from the group consisting of magnetic states, crystallographic states, and shape states, and wherein two different states selected from said at least six states are simultaneously used as operators selected from the group consisting of read and write operators, sense and indicate operators, and sense and control operators.

27. A device as in claim 26, wherein magnetoplastic and/or magnetoelastic material comprises a crystal attached to or grown on a substrate.

28. A method comprising writing data on an element and reading the data, the element comprising a magnetoplastic and/or magnetoelastic material having at least six states selected from the group consisting of magnetic states, crystallographic states, and shape states, wherein said writing comprises a step selected from the group consisting of applying a magnetic field change and applying a mechanical force to said material, and said reading the data comprises a step selected from the group consisting of atomic-force microscopy, magnetic-force microscopy, spin-polarized electrons, magneto-optical Kerr effect, and optical interferometry.

29. A method of providing logic or memory comprising displacing twin boundaries of a magnetoplastic and/or magnetoelastic material and detecting the displacement of said twin boundaries, said displacing comprising a step selected from the group consisting of applying a magnetic field change and applying a mechanical force to said material, and said detecting comprising a step selected from the group consisting of atomic-force microscopy, magnetic-force microscopy, spin-polarized electrons, magneto-optical Kerr effect, and optical interferometry, the method further comprising using said displacing and detecting for operations selected from the group consisting of reading and writing, sensing and indicating operators, and sensing and controlling.

30. A method as in claim 29, wherein said magnetoplastic and/or magnetoelastic material has at least six states comprising magnetic states, crystallographic states, and shape states.