Multi-bit memory with selectable magnetic layer

• US 8,199,570 B2
• Filed: 10/07/2010
• Issued: 06/12/2012
• Est. Priority Date: 10/07/2010
• Status: Active Grant

• Current Assignee: Everspin Technologies Incorporated
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Amin, Nurul, Van Ek, Johannes
• Primary Examiner(s): HIDALGO, FERNANDO N
• Application Number:
  US12/900,314
• Publication Number:
  US 20120087186A1
• Time in Patent Office: 614 Days
• Field of Search: 365/131, 365/158, 365/171, 365/173
• US Class Current: 365/173
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/746 Bit Patterned record carriers, wherein each magnetic isolated data island corresponds to a bit
• 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 11/1675 Writing or programming circuits or methods
• CPC Class Codes: G11C 11/5607 using magnetic storage elements

Abstract

An apparatus and associated method for a multi-bit memory capable of being selected with a magnetic layer. Various embodiments of the present invention are generally directed to a first selection layer with a low coercivity that is disposed between first and second storage layers that each have a high coercivity. In response to magnetic saturation of the first selection layer, programming of a logical state to the second storage layer is allowed.

Claims

1. An apparatus comprising:

a plurality of storage elements, each of the plurality of elements comprising a first selection layer with a low coercivity disposed between a first and second storage layers each with a high coercivity, where magnetic saturation of the first selection layer allows programming of a logical state to the second storage layer.

2. The apparatus of claim 1, wherein a first source programs the logical state and a second source saturates the selection layer.

3. The apparatus of claim 1, wherein the selection layer is a soft magnetic material that is magnetically permeable until saturated.

4. The apparatus of claim 1, wherein the storage layers are each hard magnetic materials.

5. The apparatus of claim 2, wherein the first storage layer is proximal to the first source and the second storage layer is distal to the first source so that the selection layer lies between the second storage layer and the first source.

6. The apparatus of claim 1, wherein the selection layer is saturated by magnetic fields generated outside the selection layer.

7. The apparatus of claim 1, wherein the first and second storage layers comprise a non-volatile memory cell capable of storing multiple logical states concurrently.

8. The apparatus of claim 7, wherein the selection layer is a common plane that interconnects multiple memory cells.

9. The apparatus of claim 7, wherein the selection layer is saturated by current running through the selection layer.

10. The apparatus of claim 8, wherein each memory cell has a programming source contactingly adjacent a storage layer.

11. The apparatus of claim 1, wherein the selection layer rotates about a central axis and has a first diameter.

12. The apparatus of claim 11, wherein the second storage layer has the first diameter and the first storage layer has a second diameter that is less than the first diameter.

13. The apparatus of claim 1, further comprising a third storage layer with high coercivity separated from the second storage layer by a second selection layer.

14. The apparatus of claim 1, wherein saturation of the selection layer is with a bias magnetic field that is perpendicular to a program field that programs the logical state to the second storage layer.

15. A method comprising:

providing a plurality of storage elements, each configured with a first selection layer with a low coercivity disposed between a first and second storage layers each with a high coercivity; and

programming a first logical state to the second storage layer in response to magnetic saturation of the first selection layer.

16. The method of claim 15, wherein the first selection layer is magnetically saturated with a magnetic bias field that is removed to induce the first selection layer to magnetically shield the second storage layer.

17. The method of claim 15, wherein the first storage layer is programmed with a second logical state while the first selection layer is not magnetically saturated.

18. The method of claim 15, wherein the logical state of the first and second storage layers can concurrently be read in response to the magnetic saturation of the first selection layer.

19. An apparatus comprising:

a plurality of storage elements, each of the plurality of storage elements comprising;

a first selection layer with a low coercivity disposed between a first and second storage layers each with a high coercivity, the first storage layer being proximal to a program source; and

a selection source that magnetically saturates the first selection layer with a magnetic field, the saturation of the first selection layer allowing a program field from the program source to concurrently program a first logical state to the first and second storage layers.

20. The apparatus of claim 19, wherein first storage layer is programmed to a second logical state in the absence of magnetic saturation of the first selection layer.

21. The apparatus of claim 19, wherein at least one additional selection and storage layer are attached to the second storage layer and have a corresponding additional selection source, the additional selection layer having a coercivity that allows concurrent programming of the first logical state to each storage layer upon saturation.