NANOSCALE ELECTRONIC SPIN FILTER

• US 20180019328A1
• Filed: 11/19/2015
• Published: 01/18/2018
• Est. Priority Date: 11/19/2014
• Status: Active Grant

• Current Assignee: Yeda Research and Development Co. Ltd. (Weizmann Institute of Science)
• Original Assignee: Yeda Research and Development Co. Ltd. (Weizmann Institute of Science)
• Inventors: TAL, Oren
• Granted Patent: US 10,468,507 B2
• Time in Patent Office: Days
• 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: H01F 1/0072 one dimensional, i.e. linear or dendritic nanostructures
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/329 Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect
• CPC Class Codes: H01L 29/0673 oriented parallel to a substrate
• CPC Class Codes: H01L 29/66007 Multistep manufacturing processes
• CPC Class Codes: H01L 29/66984 Devices using spin polarized carriers
• CPC Class Codes: H01L 29/7613 Single electron transistors; Coulomb blockade devices H01L29/7888 takes precedence
• CPC Class Codes: H01L 29/82 controllable by variation of the magnetic field applied to the device
• CPC Class Codes: H01L 29/84 controllable by variation of applied mechanical force, e.g. of pressure

Abstract

The present invention is in the field of spintronics, and relates to a highly efficient spin filter device, such as a spin-polarizer or a spin valve, and a method for fabrication thereof.

Claims

1. A spin filter device comprising two metal electrodes ended with low-coordinated surfaces and at least one atomic scale junction between said surfaces;

said atomic scale junction comprising;

at least one oxygen atom;

or

at least one atomic chain formed by atoms of said metal and oxygen atoms interconnected between said metal atoms;

thereby enhancing a spin-filtering effect by selective p-d orbital hybridization between the p orbitals of the oxygen and the d orbitals of the metal, promoting spin-polarized currents via frontier d orbitals of the metal and suppressing poorly spin polarized-currents via frontier s orbitals of the metal.

2. The device of claim 1, wherein said electrodes are made of a nanoscale low-coordinated structure comprising ferromagnetic or antiferromagnetic metal that chemically reacts with oxygen.

3. The device of claim 1, wherein a length of said atomic chain in said atomic scale junction is selected such that the device is operable as a spin filter.

4. The device of claim 1, wherein a length of said atomic chain in the atomic scale junction is selected such that the device is operable as a spin current conductor.

5. The device of claim 1, wherein the metal electrodes comprises at least one of the following materials:

nickel, cobalt, iron, alloys thereof.

6. The device of claim 1, wherein the current flowing through said device is at least 50% spin polarized or at least 75% spin polarized or at least 90% spin polarized.

7. The device of claim 1, wherein said device is operated at room temperature.

8. The device of claim 1 wherein said device is used as a reading probe/head of magnetic information, a memory element, a conductor for spin polarized current, or a spin current polarizer/filter or a combination thereof.

9. A method of fabrication of a spin filter device, the method comprising:

providing a wire (or a segment thereof) made of a ferromagnetic or antiferromagnetic metal;

controllably elongating a region of said wire until identifying at least one predetermined elongation condition of the wire;

exposing at least said region of the wire to oxygen environment, thereby forming in said region an atomic scale junction comprising;

at least one oxygen atom;

or

at least one atomic chain formed by the metal and oxygen atoms interconnected between the metal atoms;

resulting in a selective p-d orbital hybridization between the p orbitals of the oxygen and the d orbitals of the metal.

10. The method of claim 9, wherein said controllably elongating the region of the wire comprises monitoring at least one parameter of the wire.

11. The method of claim 9, wherein said controllably elongating the region of the wire comprises monitoring a duration of the elongation process.

12. The method of claim 9, wherein at least one parameter of the wire being monitored comprises at least one of the following:

a characteristic resistance of a single metal atom, conductance value, length of said region.

13. The method of claim 9, wherein said controllable elongation of the region of the wire and said exposing of the at least said region of the wire to the oxygen environment are performed substantially simultaneously.

14. The method of claim 9, wherein said wire is made of at least one of the following materials:

nickel, cobalt, iron, alloys thereof.

15. The method of claim 9, wherein said controllable elongation of the region of the wire and said exposing of the at least said region of the wire to the oxygen environment comprise controlling a length of the atomic chain being formed.

16. The method of claim 9, wherein said exposing of the at least elongated region of the wire to the oxygen environment comprises allowing at least partial oxidation of the wire surface to thereby form metal-oxygen atomic chains attached to the surface.

17. The method of claim 9, wherein said exposing of the at leak elongated region of the wire to the oxygen environment comprises deposition of oxygen onto said at least elongated region of the wire.

18. The method of claim 9, wherein said metal comprises at least one of the following materials:

nickel, cobalt, iron, alloys thereof.

19. A method of fabrication of the spin filter device, said method comprising:

controllably depositing a single oxygen atom or metal and oxygen atoms on a first substrate to form an oxygen atom attached to said substrate or to form at least one metal-oxygen atomic chain(s) attached to said substrate.

20. The method of claim 19, wherein at least two electrodes are fabricated on said substrate such that the tips of said electrodes are in contact with said oxygen atom or with said metal-oxygen atomic chain.

21. The method of claim 19, wherein said electrodes are fabricated prior to said deposition of oxygen or of metal and oxygen atoms or wherein said electrodes are fabricated following said deposition of oxygen or of metal and oxygen atoms.

22. The method of claim 19, wherein said substrate is insulating.

23. The method of claim 19, wherein following said metal and oxygen deposition, a second substrate is brought into contact with said metal-oxygen atomic chains, such that said first and second substrates form two electrodes in contact with said metal-oxygen atomic chains.

24. The method of claim 23, wherein said first and said second substrates or portions thereof are conductive.

25. The method of claim 20, wherein said electrodes comprise at least one of the following materials:

nickel, cobalt, iron, alloys thereof.