Annular magnetic nanostructures

• US 20050128842A1
• Filed: 11/05/2004
• Published: 06/16/2005
• Est. Priority Date: 11/07/2003
• Status: Abandoned Application

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Wei, Alexander
• Application Number:
  US10/981,921
• Publication Number:
  US 20050128842A1
• Time in Patent Office: Days
• US Class Current: 365/205
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: H01F 1/0054 Coated nanoparticles, e.g. nanoparticles coated with organic surfactant
• CPC Class Codes: H01F 1/0072 one dimensional, i.e. linear or dendritic nanostructures
• CPC Class Codes: H01F 41/26 using electric currents , e.g. electroplating
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present invention is directed to an integrated nanostructure with one or more electrically conductive nanowires and one or more annular magnetic nanostructures. Magnetic nanoparticles can form annular assemblies encircling the nanowire in the presence of a magnetic field produced by the passage of a current through the nanowire. The annular nanostructures support bistable magnetic flux closure states, which can be switched or polarized depending on the direction of the current through the nanowire.

Claims

1. A material comprising:

an electrically conductive nanowire;

one or more annular magnetic nanostructures which encircle the nanowire and are capable of supporting flux closure (FC) states, which are polarized or switched by the passage of an electrical current through the nanowire.

2. The material of claim 1 wherein the annular nanostructure is a nanoring, whose integration with the nanowire results in a nanorotaxane.

3. The material of claim 2 further comprising an additional pair of electrically conductive nanowires abutted against the nanorotaxane to produce out-of-plane magnetic fields for FC switching.

4. The material of claim 3 wherein the nanorotaxane is interdigitated between the pair of electrically conductive nanowires.

5. The material of claim 4 wherein the interdigitated conductive nanowires contain ferromagnetic domains in contact with the magnetic ring of the nanorotaxane, and serve as sense lines for spin-polarized transport.

6. The material of claim 1 wherein the annular nanostructure is a cladding.

7. The material of claim 1 wherein the nanowire is a carbon nanotube.

8. The material of claim 1 wherein the nanowire is metallic.

9. The material of claim 1 wherein the nanowire is a semiconducting nanowire.

10. The material of claim 1 wherein the nanowire has a coaxial core-shell structure.

11. The material of claim 10 wherein the core-shell structure is an inner wire sheathed in a magnetic layer.

12. The material of claim 11 further comprising a second annular structure surrounding the first annular structure and one or more additional conductive nanowires, the second annular structure being in contact with the one or more conductive nanowires, the additional conductive nanowires serving as sense lines.

13. A method of preparing nanostructures comprising:

immersion of at least one nanowire in a suspension of magnetically responsive nanoparticles; and

passage of an electrical current through the nanowire to create a magnetic field, such that the nanoparticles self-assemble into an annular nanostructure about the nanowire in the presence of the magnetic field, and a flux closure domain is created, whose polarization is induced by the direction of the current through the nanowire.

14. The method of claim 13 wherein the annular nanostructure is a semicontinuous or continuous nanoring.

15. The method of claim 13 wherein the annular nanostructure is a semicontiuous or continuous cladding.

16. The method of claim 15 wherein a second coaxial annular nanostructure forms about the first annular nanostructure.

17. The method of claim 16 further comprising placing one or more additional conductive nanowires in ohmic contact with the second annular nanostructure, to serve as sense lines.

18. The method of claim 17 wherein the additional conductive nanowires are grown radially from the second annular nanostructure.

19. The method of claim 13 further comprising interdigitating a nanorotaxane between a pair of additional conductive nanowires containing magnetic domains, such that the additional conductive nanowires serve as sense lines for spin-polarized transport.