Nonvolatile magnetic logic device

Patent metadata

Field	Value
Publication number	US-9300301-B2
Application number	US-201314649570-A
Country	US
Kind code	B2
Filing date	Dec 4, 2013
Priority date	Oct 5, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

In one aspect, a nonvolatile magnetic logic device comprises an electrically insulating layer, a write path, and a read path. The write path comprises a plurality of write path terminals and a magnetic layer having a uniform magnetization direction that is indicative of a direction of magnetization of the magnetic layer in a steady state. A logic state is written to the nonvolatile magnetic logic device by passing a current through the plurality of write path terminals. The read path comprises a plurality of read path terminals for evaluation of the logic state. The electrically insulating layer promotes electrical isolation between the read path and the write path and magnetic coupling of the read path to the write path.

First claim

What is claimed is:

1. A nonvolatile magnetic logic device, comprising:
an electrically insulating layer;
a write path adjacent to a first side of the electrically insulating layer, the write path comprising:
a plurality of write path terminals; and
a magnetic layer having a uniform magnetization direction that is indicative of a direction of magnetization of the magnetic layer in a steady state;
wherein a logic state is written to the nonvolatile magnetic logic device by passing a current through the plurality of write path terminals;
wherein the direction of magnetization of the magnetic layer represents the logic state of the nonvolatile magnetic logic device; and
wherein the direction of magnetization is configured to be controlled by a direction of the current passed through the plurality of write path terminals; and

a read path that is adjacent to a second side of the electrically insulating layer, the read path comprising a plurality of read path terminals for evaluation of the logic state;
wherein the electrically insulating layer promotes electrical isolation between the read path and the write path and magnetic coupling of the read path to the write path, wherein the electrical isolation between the read path and the write path and the magnetic coupling promote passing of the current through the plurality of write path terminals, while the logic state is evaluated among the plurality of read path terminals.

2. The nonvolatile magnetic logic device of claim 1 , wherein the read path further comprises at least one magnetic tunnel junction (MTJ) that comprises a reference layer having at least one fixed magnetization direction, a free layer having a switchable magnetization direction, and a tunnel barrier sandwiched between the reference layer and free layer.

3. The nonvolatile magnetic logic device of claim 2 , wherein the magnetic layer is a write path magnetic layer, and wherein one or more of the write path magnetic layer, the reference layer, and the free layer have an in-plane magnetic anisotropy.

4. The nonvolatile magnetic logic device of claim 2 , wherein one or more of the magnetic layer, the reference layer, and the free layer have a perpendicular magnetic anisotropy.

5. The nonvolatile magnetic logic device of claim 2 , wherein the magnetic layer and the free layer each has a shape comprising a major axis and minor axis, wherein the major axis is greater in length than the minor axis.

6. The nonvolatile magnetic logic device of claim 2 , wherein the shape comprises one or more of a rectangular shape and an elliptical shape.

7. The nonvolatile magnetic logic device of claim 2 , wherein the read path further comprises a synthetic antiferromagnetic layer that pins the at least one fixed magnetization direction of the reference layer of the at least one MTJ.

8. The nonvolatile magnetic logic device of claim 2 , wherein the read path has a first resistance when the magnetization directions of the reference layer and the free layer are substantially parallel, and the read path has a second resistance when the magnetization directions of the reference layer and the free layer are substantially antiparallel.

9. The nonvolatile magnetic logic device of claim 8 , wherein the free layer is configured to switch with the magnetization direction of the write path, and the concurrent switching of the switchable magnetization direction causes a resistance of the read path to switch between the first resistance and the second resistance to promote evaluation of the logic state.

10. The nonvolatile magnetic logic device of claim 8 , wherein the second resistance has an increased value relative to a value of the first resistance.

11. The nonvolatile magnetic logic device of claim 1 , wherein the second side of the electrically insulating layer is opposite to the first side of the electrically insulating layer.

12. The nonvolatile magnetic logic device of claim 1 , wherein the write path further comprises an underlayer and a capping layer, and the magnetic layer is positioned between the underlayer and the capping layer.

13. The nonvolatile magnetic logic device of claim 1 , wherein the read path further comprises a first magnetic tunnel junction (MTJ) that comprises a first reference layer that is separate from a second reference layer of a second MTJ and wherein the first MTJ further comprises a free layer that is shared with the second MTJ.

14. The nonvolatile magnetic logic device of claim 1 , wherein the read path further comprises at least one magnetic tunnel junction (MTJ), and wherein a read path terminal of the plurality of read path terminals is electrically coupled to a free layer of the at least one MTJ via an ohmic contact.

15. The nonvolatile magnetic logic device of claim 2 , wherein the magnetic layer of the write path is ferromagnetically coupled to the free layer.

16. The nonvolatile magnetic logic device of claim 2 , wherein the magnetic layer of the write path is antiferromagnetically coupled to the free layer.

17. The nonvolatile magnetic logic device of claim 1 , wherein the magnetic layer of the write path comprises two or more sub-layers;
wherein each of the two or more sub-layers comprises a magnetic material;
wherein a first sub-layer of the two or more sub-layers has a thickness that differs from a thickness of a second sub-layer of the two more sub-layers;
wherein an adjacent layer of the two or more sub-layers is separated by a conductive spacer; and
wherein magnetization directions of the adjacent layers of the two or more sub-layers are substantially antiparallel.

18. The nonvolatile magnetic logic device of claim 1 , wherein the electrically insulating layer comprises a magnetic material.

19. The nonvolatile magnetic logic device of claim 1 , wherein the electrically insulating layer comprises a non-magnetic material.

20. The nonvolatile magnetic logic device of claim 1 , wherein the direction of magnetization of the magnetic layer of the write path is further configured to be controlled using a bias magnetic field.

21. The nonvolatile magnetic logic device of claim 1 , wherein the read path further comprises a giant magnetoresistive (GMR) sensor comprising a reference layer having at least one fixed magnetization direction, a free layer having a switchable magnetization direction, and a conductive interlayer sandwiched between the reference layer and free layer.

22. The nonvolatile magnetic logic device of claim 21 , wherein the read path further comprises a synthetic antiferromagnetic layer that pins the at least one fixed magnetization direction of the reference layer of the at least one GMR sensor.

23. A nonvolatile magnetic logic device, comprising:
a write path comprising:
a plurality of write path terminals each comprising at least one of gold, silver, platinum, copper, tungsten, and aluminum;
a write path magnetic layer comprising at least one of iron, cobalt, and nickel, the magnetic layer having a uniform magnetization direction that is indicative of a direction of magnetization of the magnetic layer in a steady state;
wherein a logic state is written to the nonvolatile magnetic logic device by passing a current through the plurality of write path terminals;
wherein the direction of magnetization of the write path magnetic layer represents the logic state of the nonvolatile magnetic logic device; and
wherein the direction of magnetization is configured to be controlled by a direction of the current passe

Assignees

• Univ Carnegie Mellon

Inventors

• Bromberg David M
• Zhu Jian-Gang
• Pileggi Lawrence
• Sokalski Vincent
• Moneck Matthew

Classifications

• H03K19/20

  characterised by logic function, e.g. AND, OR, NOR, NOT circuits (H03K19/003 - H03K19/01 take precedence) · CPC title

• H03K19/18 Primary

  using galvano-magnetic devices, e.g. Hall-effect devices · CPC title

• H01L43/08

  Electricity · mapped topic

• G11C11/1675

  Writing or programming circuits or methods · CPC title

• G11C11/161

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title