REFERENCE LAYER FOR PERPENDICULAR MAGNETIC ANISOTROPY MAGNETIC TUNNEL JUNCTION

• US 20150263266A1
• Filed: 08/15/2014
• Published: 09/17/2015
• Est. Priority Date: 03/12/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhu, Xiaochun, Lee, Kangho, Kang, Seung Hyuk, Gottwald, Matthias Georg, Park, Chando
• Granted Patent: US 9,583,696 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

An apparatus includes a perpendicular magnetic anisotropy magnetic tunnel junction (pMTJ) device. The pMTJ device includes a storage layer and a reference layer. The reference layer includes a portion configured to produce a ferrimagnetic effect. The portion includes a first layer, a second layer, and a third layer. The second layer is configured to antiferromagnetically (AF) couple the first layer and the third layer during operation of the pMTJ device.

Claims

1. An apparatus comprising:

a storage layer of a perpendicular magnetic anisotropy magnetic tunnel junction (pMTJ) device; and

a reference layer of the pMTJ device,

wherein the reference layer comprises a portion configured to produce a ferrimagnetic effect, the portion comprising a first layer, a second layer, and a third layer, and wherein the second layer is configured to antiferromagnetically (AF) couple the first layer and the third layer during operation of the pMTJ device.

2. The apparatus of claim 1, wherein the reference layer further comprises a fourth layer, wherein the first layer, the second layer, the third layer, and the fourth layer form a first cobalt/iridium (Co/Ir) multilayer structure, and wherein the reference layer further comprises a second Co/Ir multilayer structure.

3. The apparatus of claim 2, wherein the reference layer comprises a positive integer number of N Co/Ir multilayer structures, and wherein N is selected based on a stray dipolar magnetic field associated with the pMTJ device.

4. The apparatus of claim 1, wherein the reference layer is associated with a stray dipolar magnetic field during operation of the pMTJ device, and wherein the reference layer is further configured to locally reduce the stray dipolar magnetic field via the ferrimagnetic effect during operation of the pMTJ device.

5. The apparatus of claim 1, wherein the first layer comprises a first material, wherein the second layer comprises a second material, and wherein the third layer comprises the first material.

6. The apparatus of claim 5, wherein the first material comprises cobalt (Co), and wherein the second material comprises iridium (Ir).

7. The apparatus of claim 1, wherein the reference layer further comprises a junction between the first layer and the second layer that is configured to enable a perpendicular magnetic anisotropy (PMA) of the pMTJ device.

8. The apparatus of claim 1, wherein the portion is a multilayer synthetic ferrimagnet (SFi).

9. The apparatus of claim 1, further comprising a magnetoresistive random access memory (MRAM) device that comprises the pMTJ device.

10. The apparatus of claim 9, further comprising an electronic device selected from a mobile device, a computer, a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), or a fixed location data unit, wherein the MRAM device is integrated within the electronic device.

11. A method comprising:

biasing a perpendicular magnetic anisotropy magnetic tunnel junction (pMTJ) device to generate a magnetic state at the pMTJ device; and

initiating a sense operation to determine the magnetic state using a reference layer of the pMTJ device,

wherein the reference layer comprises a portion that produces a ferrimagnetic effect, the portion comprising a first layer, a second layer, and a third layer, and wherein the second layer antiferromagnetically (AF) couples the first layer and the third layer during the sense operation.

12. The method of claim 11, wherein the magnetic state corresponds to either a parallel magnetic state of a storage layer of the pMTJ device relative to the reference layer or to an anti-parallel magnetic state of the storage layer relative to the reference layer.

13. The method of claim 11, wherein the magnetic state indicates one of a first logical bit value or a second logical bit value.

14. The method of claim 11, wherein biasing the pMTJ device comprises applying a bias signal to an electrode of the pMTJ device to generate a switching current through the pMTJ device.

15. The method of claim 11, wherein the pMTJ device is integrated within a magnetoresistive random access memory (MRAM) device, and wherein the pMTJ is sensed using a sense amplifier of the MRAM device.

16. The method of claim 11, wherein the reference layer is associated with a stray dipolar magnetic field during operation of the pMTJ device, and wherein the portion is further configured to locally reduce the stray dipolar magnetic field via the ferrimagnetic effect during operation of the pMTJ device.

17. An apparatus comprising:

means for generating a configurable magnetic state of a perpendicular magnetic anisotropy magnetic tunnel junction (pMTJ) device; and

means for generating a reference magnetic state of the pMTJ device,

wherein the means for generating the reference magnetic state comprises means for producing a ferrimagnetic effect, the means for generating the ferrimagnetic effect comprising means for generating a first magnetic field, means for generating a second magnetic field, and means for antiferromagnetically (AF) coupling the means for generating the first magnetic field and the means for generating the second magnetic field.

18. The apparatus of claim 17, wherein the means for generating the configurable magnetic state comprises a storage layer of the pMTJ device.

19. The apparatus of claim 17, wherein the means for generating the reference magnetic state corresponds to a reference layer of the pMTJ device.

20. The apparatus of claim 17, wherein the means for generating the first magnetic field, the means for generating the second magnetic field, and the means for AF coupling form a multilayer synthetic ferrimagnet (SFi).

21. The apparatus of claim 17, wherein the means for generating the first magnetic field comprises a first layer of a first material, and wherein the means for AF coupling comprises a second layer of a second material.

22. The apparatus of claim 21, wherein the means for generating the second magnetic field comprises a third layer of the first material, wherein the first material comprises cobalt (Co), and wherein the second material comprises iridium (Ir).

23. The apparatus of claim 21, further comprising a junction between the first layer and the second layer that is configured to generate a perpendicular magnetic anisotropy (PMA) of the pMTJ device.

24. The apparatus of claim 17, wherein the means for generating the ferrimagnetic effect comprises a cobalt/iridium (Co/Ir) multilayer structure.

25. The apparatus of claim 17, further comprising a magnetoresistive random access memory (MRAM) device that comprises the pMTJ device.

26. The apparatus of claim 25, further comprising an electronic device selected from a mobile device, a computer, a set top box, a music player, a video player, an entertainment unit, a navigation device, a communications device, a personal digital assistant (PDA), or a fixed location data unit, wherein the MRAM device is integrated within the electronic device.

27. A computer-readable medium storing instructions that are executable by a processor, the computer-readable medium comprising a perpendicular magnetic anisotropy magnetic tunnel junction (pMTJ) device comprising:

a storage layer; and

a reference layer,

wherein the reference layer comprises a portion configured to produce a ferrimagnetic effect, the portion comprising a first layer, a second layer, and a third layer, and wherein the second layer is configured to antiferromagnetically (AF) couple the first layer and the third layer during operation of the pMTJ device.

28. The computer-readable medium of claim 27, wherein the pMTJ device stores a particular bit value of the instructions.

29. The computer-readable medium of claim 27, integrated within a magnetoresistive random access memory (MRAM) device.

30. The computer-readable medium of claim 27, integrated within a mobile device.