Spintronic circuit and method of operation therefore

Patent metadata

Field	Value
Publication number	US-9361963-B2
Application number	US-201314415048-A
Country	US
Kind code	B2
Filing date	Jul 3, 2013
Priority date	Jul 19, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

The invention relates to a spintronic circuit ( 10; 11; 15 ) comprising: a conductive non-magnetic channel ( 1 ); —means ( 2 , NM, FM 1 -FM 3 ) for generating spin polarized electrons ( 4 ) in the non-magnetic channel ( 1 ) by spin extraction; at least two ferromagnetic contacts (FM 1 -FM 3 ) arranged along the non-magnetic channel ( 1 ) one after another, —means ( 7, 8, 9 ) for adjusting the magnetization direction of the ferromagnetic contacts (FM 1 -FM 3 ); means for propagating the spin polarized electrons ( 4 ) along the non-magnetic channel ( 1 ); means ( 5, 6 ) for measuring the contact resistance of the individual ferromagnetic contacts (FM 1 -FM 3 ), wherein the contact resistance depends on the relative alignment of the spin polarization direction of the spin polarized electrons ( 4 ) in the non-magnetic channel ( 1 ) at the ferromagnetic contact (FM 1 -FM 3 ) and the magnetization direction of the ferromagnetic contact (FM 1 -FM 3 ).

First claim

The invention claimed is:

1. Spintronic circuit comprising:
a) a conductive non-magnetic channel,
b) means for generating spin polarized electrons in the non-magnetic channel, and
c) at least two ferromagnetic contacts arranged on the non-magnetic channel, wherein the ferromagnetic contacts each have an adjustable magnetization direction and a variable contact resistance, and
d) means for adjusting the magnetization direction of the ferromagnetic contacts,
e) wherein the ferromagnetic contacts are arranged on the non-magnetic channel along the non-magnetic channel one after another, and
f) the means for generating the spin polarized electrons operate by spin extraction upon a net electron flow from the non-magnetic channel to one of the ferromagnetic contacts, and
g) the spintronic circuit comprises a means for propagating the spin polarized electrons by way of drift along the non-magnetic channel caused by an applied electric field, and
h) the spintronic circuit comprises means for measuring the contact resistances of the individual ferromagnetic contacts, wherein the contact resistances depend on the relative alignment of the spin polarization direction of the spin polarized electrons in the non-magnetic channel at the ferromagnetic contact on the one hand and the magnetization direction of the ferromagnetic contact on the other hand.

2. Spintronic circuit according to claim 1 , wherein the means for generating the spin polarized electrons in the non-magnetic channel comprise:
a) a non-magnetic contact arranged on the non-magnetic channel, and
b) a first current source connected to the non-magnetic contact on the non-magnetic channel for injecting electrons into the non-magnetic channel, and
c) spin extraction upon electron flow into a ferromagnetic contact.

3. Spintronic circuit according to claim 2 , wherein a) the non-magnetic channel has a characteristic spin diffusion length, so that the spin polarization of the spin polarized electrons substantially decays after diffusion over the spin diffusion length, and b) there is a specific separation between the adjacent ferromagnetic contacts on the non-magnetic channel, wherein said separation is smaller than the spin diffusion length, so that the electron spin polarization does not substantially decay during propagation from one of the ferromagnetic contacts to the next one of the ferromagnetic contacts.

4. Spintronic circuit according to claim 1 , wherein the spin polarization direction of the spin polarized electrons in the non-magnetic channel arriving at each ferromagnetic contact is determined by the spin extraction at the preceding ferromagnetic contacts along the channel.

5. Spintronic circuit according to claim 1 , wherein the means for adjusting the magnetization direction of the ferromagnetic contacts comprise a current carrying conductor generating a stray field.

6. Spintronic circuit according to claim 1 , wherein the magnetization direction of one of the ferromagnetic contacts is fixed in order to achieve a unique electric output for each of the magnetization configurations.

7. Spintronic circuit according to claim 6 , wherein the ferromagnetic contact with the fixed magnetization direction has a higher coercivity than the other ferromagnetic contacts.

8. Spintronic circuit according to claim 6 , wherein the ferromagnetic contact with the fixed magnetization direction is exchange-biased using an adjacent anti-ferromagnetic layer.

9. Spintronic circuit according to claim 1 , wherein
a) the spintronic circuit is a memory circuit comprising several 1-Bit memory cells each associated with one of the ferromagnetic contacts, wherein in each of the memory cells the magnetization direction of the ferromagnetic contact represents the binary state of the memory cell, and
b) the electric output measured by the measuring unit is a multi-level output, so that a single measurement by the measuring unit represents the binary states of all memory cells of the memory circuit.

10. Spintronic circuit according to claim 1 , wherein
a) the spintronic circuit is a logic circuit performing a logic operation, wherein the logic circuit comprises several inputs and one output, and
b) the output of the logic circuit is associated with the electric multi-level output measured by the measuring unit, and
c) the inputs are each associated with the magnetization direction of one of the ferromagnetic contacts.

11. Spintronic circuit according to claim 10 , wherein
a) the inputs and the output of the logic circuit are binary, and
b) one or more of the values of the multi-level output are associated to one binary value, while the other values of the multi-level output are associated to the other binary value.

12. Spintronic circuit according to claim 10 , wherein at least one of the ferromagnetic contacts is a programming input, so that the magnetization direction of said programming input defines the type of the logic operation performed by the logic circuit.

13. Spintronic circuit according to claim 1 , wherein the means for adjusting the magnetization direction of the ferromagnetic contacts comprise a spin-transfer torque mechanism.

14. Spintronic circuit according to claim 1 , wherein the spintronic circuit is a memory circuit.

15. Spintronic circuit according to claim 1 , wherein the spintronic circuit is a logic circuit.

16. Method of operation of a spintronic circuit comprising a non-magnetic channel and at least two ferromagnetic contacts arranged on the non-magnetic channel, wherein the method comprises the following steps:
a) adjusting the magnetization direction of the ferromagnetic contacts,
b) generating spin polarized electrons in the non-magnetic channel by spin extraction upon a net electron flow from the non-magnetic channel to the ferromagnetic contacts,
c) propagation of the spin polarized electrons along the non-magnetic channel by an electric field, and
d) measuring a contact resistance of at least one of the ferromagnetic contacts, wherein the contact resistance depends on the relative alignment of the spin polarization direction of the spin polarized electrons in the non-magnetic channel at the ferromagnetic contact on the one hand and the magnetization direction of the ferromagnetic contact on the other hand.

17. Spintronic circuit comprising:
a) a conductive non-magnetic channel,
b) means for generating spin polarized electrons in the non-magnetic channel, and
c) at least two ferromagnetic contacts arranged on the non-magnetic channel, wherein the ferromagnetic contacts each have an adjustable magnetization direction and a variable contact resistance, and
d) means for adjusting the magnetization direction of the ferromagnetic contacts,
e) wherein the ferromagnetic contacts are arranged on the non-magnetic channel along the non-magnetic channel one after another, and
f) the means for generating the spin polarized electrons operate by spin extraction upon a net electron flow from the non-magnetic channel to one of the ferromagnetic contacts, and
g) the spintronic circuit comprises a means for propagating the spin polarized electrons by way of drift along the non-magnetic channel caused by an applied electric field, and
h) the spintronic circuit comprises means for measuring the contact resistances of the individual ferromagnetic contacts, wherein the contact resistances depend on the relative alignment of the spin polarization direction of the spin polarized electrons in the non-magnetic channel at the ferromagnetic contact on the one hand and the magnetization direction of the ferromagnetic

Assignees

• Forschungsverbund Berlin Ev

Inventors

• Manzke Yori
• Farshchi Rouin
• Ramsteiner Manfred

Classifications

• G11C19/0808

  using magnetic domain propagation · CPC title

• G11C11/16

  using elements in which the storage effect is based on magnetic spin effect · CPC title

• G11C29/50008

  of impedance · CPC title

• G11C11/1675

  Writing or programming circuits or methods · CPC title

• G11C11/1673

  Reading or sensing circuits or methods · CPC title