Magnetic memory cell structure with spin device elements and method of operating the same

• US 9,552,860 B2
• Filed: 07/31/2015
• Issued: 01/24/2017
• Est. Priority Date: 04/01/2015
• Status: Active Grant

• Current Assignee: Bluespin, Inc.
• Original Assignee: Bluespin, Inc.
• Inventors: Fukuzawa, Hideaki
• Primary Examiner(s): PHAN, TRONG Q
• Application Number:
  US14/815,217
• Publication Number:
  US 20160293240A1
• Time in Patent Office: 543 Days
• Field of Search: 365/158, 365/171, 365/173
• 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 11/1659 Cell access
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details

Abstract

A magnetic memory includes a plurality of memory cells and a data identification circuit. Each of the memory cells includes: a first bias node to which a first voltage is applied in data reading, the first voltage being a positive voltage; a second bias node to which a second voltage is applied in the data reading, the second voltage being a negative voltage having substantially the same absolute value as the first voltage; a connection node; a first spin device element connected between the first bias node and the connection node; and a second spin device element connected between the connection node and the second bias node. The first and second spin device elements operate differentially. The data identification circuit identifies data stored in each of the memory cells based on a polarity of a voltage generated on the connection node.

Claims

1. A magnetic memory, comprising:

a plurality of memory cells; and

a data identification circuit,

wherein each of the memory cells includes;

a first bias node to which a first voltage is applied in a data reading, the first voltage being a positive voltage;

a second bias node to which a second voltage is applied in the data reading, the second voltage being a negative voltage having substantially a same absolute value as the first voltage;

a connection node;

a first spin device element connected between the first bias node and the connection node; and

a second spin device element connected between the connection node and the second bias node,

wherein each of the first and second spin device elements is configured to have a first magnetization which is reversible and to take a selected one of first and second states depending on a direction of the first magnetization,

wherein the first and second spin device elements are placed in different states selected from the first and second states, and

wherein the data identification circuit identifies a data stored in each of the memory cells based on a polarity of a voltage generated on the connection node.

2. The magnetic memory according to claim 1, wherein each of the first and second spin device elements includes:

a recording layer having the first magnetization;

a reference layer having a second magnetization which is fixed; and

a spacer layer provided between the recording layer and the reference layer,

wherein the first and second spin device elements in each of the memory cells are connected with the recording layers thereof connected to each other, or with the reference layers thereof connected to each other.

3. The magnetic memory according to claim 1, further comprising:

a deformable base plate; and

a bending mechanism configured to bend the deformable base plate,

wherein the first and second spin device elements are coupled with the deformable base plate, and

wherein at least one of upper and lower surfaces of the deformable base plate faces a space which is not filled with a solid substance.

4. The magnetic memory according to claim 3, wherein the bending mechanism is configured to bend the deformable base plate with a piezoelectric effect.

5. The magnetic memory according to claim 3, wherein the first and second spin device elements are positioned opposed to the space which is not filled with a solid substance, across the deformable base plate.

6. The magnetic memory according to claim 5, wherein the first and second spin device elements are coupled with an upper surface of the deformable base plate, and

wherein the lower surface of the deformable base plate faces the space which is not filled with a solid substance.

7. The magnetic memory according to claim 3, wherein the bending mechanism includes a piezoelectric layer coupled with a side surface of the deformable base plate.

8. A magnetic memory, comprising:

a memory cell; and

a data identification circuit,

wherein the memory cell includes;

a first bias node to which a first voltage is applied in a data reading from the memory cell;

a second bias node to which a second voltage lower than the first voltage is applied in the data reading;

a first connection node;

a second connection node;

a first spin device element connected between the first bias node and the first connection node;

a second spin device element connected between the first connection node and the second bias node;

a third spin device element connected between the first bias node and the second connection node; and

a fourth spin device element connected between the second connection node and the second bias node,

wherein each of the first to fourth spin device elements is configured to have a first magnetization which is reversible and to take a selected one of first and second states depending on a direction of the first magnetization,

wherein the first and fourth spin device elements have a same state selected from the first and second states,

wherein the second and third spin device elements have a same state selected from the first and second states,

wherein the first and fourth spin device elements are placed in a different state from the second and third spin device elements, and

wherein the data identification circuit identifies a data stored in the memory cell based on a voltage generated between the first connection node and the second connection node.

9. The magnetic memory according to claim 8, wherein the data identification circuit identifies a data stored in the memory cell based on which of a third voltage and a fourth voltage is higher, the third voltage being a voltage generated on the first connection node and the fourth voltage being a voltage generated on the second connection node.

10. The magnetic memory according to claim 8, wherein the first spin device element is connected between a third connection node and the first connection node,

wherein the second spin device element is connected between the first connection node and a fifth connection node,

wherein the third spin device element is connected between a fourth connection node and the second connection node,

wherein the fourth spin device element is connected between the second connection node and the fifth connection node,

wherein the third connection node is connected to the first bias node,

wherein the memory cell further includes:

a first switching element configured to connect the fourth connection node to selected one of the first bias node and a third bias node having a predetermined voltage; and

a second switching element connected between the fifth connection node and the second bias node.

11. The magnetic memory according to claim 10, wherein, in the data reading, the first switching element connects the fourth connection node to the first bias node and the second switching element connects the fifth connection node to the second bias node.

12. The magnetic memory according to claim 10, wherein, in a data writing into the memory cell, the first switching element connects the fourth connection node to the third bias node and the second switching element disconnects the fifth connection node from the second bias node, and

wherein, in the data writing, a selected one of a voltage higher than the predetermined voltage on the third bias node and a voltage lower than the predetermined voltage is applied to the first bias node, in response to a data to be written into the memory cell.

13. The magnetic memory according to claim 8, wherein the first spin device element is connected between a third connection node and the first connection node,

wherein the second spin device element is connected between the first connection node and a fifth connection node,

wherein the third spin device element is connected between a fourth connection node and the second connection node,

wherein the fourth spin device element is connected between the second connection node and the fifth connection node,

wherein the fourth connection node is connected to the first bias node,

wherein the memory cell further includes:

a first switching element configured to connect the third connection node to selected one of the first bias node and a third bias node having a predetermined voltage; and

a second switching element connected between the fifth connection node and the second bias node.

14. The magnetic memory according to claim 13, wherein, in the data reading, the first switching element connects the third connection node to the first bias node and the second switching element connects the fifth connection node to the second bias node.

15. The magnetic memory according to claim 13, wherein, in a data writing into the memory cell, the first switching element connects the third connection node to the third bias node and the second switching element disconnects the fifth connection node from the second bias node, and

wherein, in the data writing, a selected one of a voltage higher than the predetermined voltage on the third bias node and a voltage lower than the predetermined voltage is applied to the first bias node, in response to a data to be written into the memory cell.

16. The magnetic memory according to claim 10, wherein each of the first to fourth spin device elements includes:

a recording layer having the first magnetization;

a reference layer having a second magnetization which is fixed; and

a spacer layer provided between the recording layer and the reference layer,

wherein, in a route along which the third and fourth connection nodes are connected via the first to fourth spin device elements, adjacent two spin device elements of the first to fourth spin device elements are connected, with the recording layers thereof connected to each other, or with the reference layers thereof connected to each other.

17. The magnetic memory according to claim 13, wherein each of the first to fourth spin device elements includes:

a recording layer having the first magnetization;

a reference layer having a second magnetization which is fixed; and

a spacer layer provided between the recording layer and the reference layer,

wherein, in a route along which the third and fourth connection nodes are connected via the first to fourth spin device elements, adjacent two spin device elements of the first to fourth spin device elements are connected, with the recording layers thereof connected to each other, or with the reference layers thereof connected to each other.

18. The magnetic memory according to claim 8, further comprising:

a write current line provided close to the memory cell to extend in a first direction,

wherein the first and third spin device elements are positioned shifted from the write current line in a second direction perpendicular to the first direction,

wherein the second and fourth spin device elements are positioned shifted from the write current line in a third direction opposite to the second direction, and

wherein, in data writing into the memory cell, a write current is generated through the write current line in a direction depending on a data to be written into the memory cell.

19. The magnetic memory according to claim 8, further including:

a deformable base plate; and

a bending mechanism configured to bend the deformable base plate,

wherein the first to fourth spin device elements are coupled with the deformable base plate, and

wherein at least one of upper and lower surfaces of the deformable base plate faces a space which is not filled with a solid substance.

20. The magnetic memory according to claim 19, wherein the bending mechanism is configured to bend the deformable base plate with a piezoelectric effect.

21. The magnetic memory according to claim 19, wherein the first to fourth spin device elements are positioned opposed to the space which is not filled with a solid substance, across the deformable base plate.

22. The magnetic memory according to claim 21, wherein the first to fourth spin device elements are coupled with an upper surface of the deformable base plate, and

wherein the lower surface of the deformable base plate faces the space which is not filled with a solid substance.

23. The magnetic memory according to claim 19, wherein the bending mechanism includes a piezoelectric layer coupled with a side surface of the deformable base plate.

24. A magnetic memory, comprising:

a memory cell; and

a data identification circuit,

wherein the memory cell includes;

a first bias node to which a first voltage is applied in a data reading from the memory cell;

a second bias node to which a second voltage lower than the first voltage is applied in the data reading;

a first connection node;

a second connection node;

a first spin device element connected between the first bias node and the first connection node;

a first resistor element connected between the first connection node and the second bias node;

a second resistor element connected between the first bias node and the second connection node; and

a second spin device element connected between the second connection node and the second bias node,

wherein each of the first and second spin device elements is configured to have a first magnetization which is reversible and to take a selected one of first and second states depending on a direction of the first magnetization,

wherein the first and second spin device elements have a same state selected from the first and second states,

wherein the data identification circuit identifies a data stored in each of the memory cells based on a voltage generated between the first connection node and the second connection node.

25. The magnetic memory according to claim 24, wherein the data identification circuit identifies a data stored in the memory cell based on which of a third voltage and a fourth voltage is higher, the third voltage being a voltage generated on the first connection node and the fourth voltage being a voltage generated on the second connection node.

26. A method of operating a magnetic memory including a plurality of memory cells each comprising first and second bias nodes, a connection node, a first spin device element connected between the first bias node and the connection node, and a second spin device element connected between the connection node and the second bias node,

wherein each of the first and second spin device elements is configured to have a first magnetization which is reversible and to take selected one of first and second states depending on a direction of the first magnetization,

wherein the first and second spin device elements are placed in different states selected from the first and second states,

the method comprising:

applying a first voltage to the first bias node, the first voltage being a positive voltage;

applying a second voltage to the second bias node, the second voltage being a negative voltage having substantially a same absolute value as the first voltage; and

identifying a data stored in each of the memory cells based on a polarity of a voltage generated on the connection node.

27. A method of operating a magnetic memory which includes a memory cell comprising:

first and second bias nodes;

first and second connection nodes;

a first spin device element connected between the first bias node and the first connection node;

a second spin device element connected between the first connection node and the second bias node;

a third spin device element connected between the first bias node and the second connection node; and

a fourth spin device element connected between the second connection node and the second bias node,

wherein each of the first to fourth spin device elements is configured to have a first magnetization which is reversible and to take selected one of first and second states depending on a direction of the first magnetization,

wherein the first and fourth spin device elements have a same state selected from the first and second states,

wherein the second and third spin device elements have a same state selected from the first and second states, and

wherein the first and fourth spin device elements are placed in a different state from the second and third spin device elements,

the method comprising;

applying a first voltage to the first bias node;

applying a second voltage lower than the first voltage to the second bias node; and

identifying a data stored in the memory cell based on a third voltage generated on the first connection node and a fourth voltage generated on the second connection node.