Magnetic memory device having soft reference layer

• US 6,750,491 B2
• Filed: 12/20/2001
• Issued: 06/15/2004
• Est. Priority Date: 12/20/2001
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Sharma, Manish, Tran, Lung, Anthony, Thomas C.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): TRAN, MAI HUONG C
• Application Number:
  US10/029,694
• Publication Number:
  US 20030117840A1
• Time in Patent Office: 908 Days
• Field of Search: 257/421, 257/422, 257/428, 365/171, 365/173, 365/151, 365/158
• US Class Current: 257/295
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods

Abstract

A magnetic memory device includes first and second ferromagnetic layers. Each ferromagnetic layer has a magnetization that can be oriented in either of two directions. The first ferromagnetic layer has a higher coercivity than the second ferromagnetic layer. The magnetic memory device further includes a structure for forming a closed flux path with the second ferromagnetic layer.

Claims

1. A magnetic memory device comprising:

first and second ferromagnetic layers, each ferromagnetic layer having a magnetization that can be oriented in either of two directions, the first ferromagnetic layer having a higher coercivity than the second ferromagnetic layer; and

a structure for forming a closed flux path with the second ferromagnetic layer.

2. The device of claim 1, wherein the structure includes a conductor clad with ferromagnetic material, portions of the ferromagnetic material in magnetic communication with the second ferromagnetic layer.

3. The device of claim 2, wherein all but a surface of the conductor is clad, wherein the unclad surface is in direct contact with the second ferromagnetic layer.

4. The device of claim 2, wherein portions of the ferromagnetic material define a magnetic gap, the portions in direct contact with the second ferromagnetic layer.

5. The device of claim 1, wherein the first layer is a data layer, and the second layer is a reference layer.

6. The device of claim 5, wherein the data layer and the reference layer are made of at least one of different shapes, thickness and ferromagnetic materials.

7. The device of claim 1, further comprising an insulating tunnel barrier between the ferromagnetic layers.

8. The device of claim 1, further comprising a non-magnetic metallic layer between the ferromagnetic layers.

9. A device comprising:

a magnetic tunnel junction including first and second ferromagnetic layers; and

means for forming a closed flux path with one of the ferromagnetic layers.

10. A structure for a magnetic memory device including a ferromagnetic layer, the structure comprising:

an electrical conductor; and

ferromagnetic cladding on the conductor, the ferromagnetic cladding forming a closed flux path with the ferromagnetic layer.

11. The structure of claim 10, wherein all but a surface of the conductor is clad, wherein the unclad surface is in direct contact with the ferromagnetic layer.

12. The structure of claim 10, wherein portions of the ferromagnetic cladding define a magnetic gap, the portions in direct contact with the ferromagnetic layer.

13. The structure of claim 10, wherein the ferromagnetic layer is a reference layer, whereby the cladding forms a closed flux path with the reference layer of the magnetic memory device.