SPIN TRANSFER TORQUE MAGNETIC MEMORY DEVICE USING MAGNETIC RESONANCE PRECESSION AND THE SPIN FILTERING EFFECT

• US 20140159175A1
• Filed: 04/30/2012
• Published: 06/12/2014
• Est. Priority Date: 05/12/2011
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Korea University Research and Business Foundation
• Inventors: Lee, Kyung-Jin, Seo, Soo-Man
• Application Number:
  US14/116,959
• Publication Number:
  US 20140159175A1
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

The present invention relates to a magnetic memory device which additionally comprises a free magnetic layer constituting a horizontal direction variable magnetization layer having a fixed saturation magnetization value, whereby a switching current is markedly reduced as compared with conventional magnetic layers such that a high degree of integration of the device can be achieved and it is possible to lower a critical current density necessary for magnetization reversal thereby reducing the power consumption of the device. Also, a stray field effect occurring from a fixed magnetic layer is reduced such that a written magnetization data is thermally stable.

Claims

1. A magnetic memory device comprising:

a first fixed magnetic layer;

a first free magnetic layer; and

a second free magnetic layer,

wherein the first fixed magnetic layer is a thin layer formed of a material that has a fixed magnetization direction and that is magnetized in a perpendicular direction to a plane of the layer,

wherein the first free magnetic layer is a thin layer formed of a material that has a magnetization direction changed by a current applied from the outside and that is magnetized in a perpendicular direction to a plane of the layer,

wherein the second free magnetic layer is a thin layer formed of a material that has a magnetization direction changed by a current applied from the outside and that is magnetized in a horizontal direction to a plane of the layer, and

wherein a first non-magnetic layer and a second non-magnetic layer are disposed between the first fixed magnetic layer and the first free magnetic layer and between the first free magnetic layer and the second free magnetic layer, respectively.

2. The magnetic memory device of claim 1, further comprising:

a second fixed magnetic layer; and

a third non-magnetic layer between the second free magnetic layer and the second fixed magnetic layer, and

wherein the second fixed magnetic layer is a thin layer formed of a material that has a fixed magnetization direction opposite to the first fixed magnetic layer and that is magnetized in a perpendicular direction to a plane of the layer.

3. The magnetic memory device of claim 1, wherein a saturation magnetization value of the material magnetized in the horizontal direction is in a range of 300˜

2000 kA/m.

4. The magnetic memory device of claim 1 or 2, wherein the first fixed magnetic layer and the second fixed magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

5. The magnetic memory device of claim 4, wherein the first fixed magnetic layer and the second fixed magnetic layer are a multi-thin layer consisting of n stacked double layer (n≧

1), respectively,

wherein the double layer consists of an X layer and a Y layer, and

wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Tb, Zr, Pt, Pd, and a mixture thereof.

6. The magnetic memory device of claim 1 or 2, wherein at least one of the first fixed magnetic layer and the second fixed magnetic layer has an anti-magnetic structure consisting of a first magnetic layer, a non-magnetic layer and a second magnetic layer, and

wherein the first magnetic layer and the second magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

7. The magnetic memory device of claim 6, wherein at least one of the first magnetic layer and the second magnetic layer is a multi-thin layer consisting of n stacked double layer (n≧

1),

wherein the double layer consists of an X layer and a Y layer, and

wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

8. The magnetic memory device of claim 1 or 2, wherein at least one of the first fixed magnetic layer and the second fixed magnetic layer has an exchange biased anti-magnetic structure consisting of an antiferromagnetic layer, a first magnetic layer, a non-magnetic layer and a second magnetic layer,

wherein the antiferromagnetic layer is formed of a material selected from a group consisting of Ir, Pt, Mn, and a mixture thereof, and

wherein the first magnetic layer and the second magnetic layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

9. The magnetic memory device of claim 8, wherein at least one of the first magnetic layer and the second magnetic layer is a multi-thin layer consisting of n stacked double layer (n≧

1),

wherein the double layer consists of an X layer and a Y layer, and

wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

10. The magnetic memory device of claim 1 or 2, wherein the first fixed magnetic layer and the second fixed magnetic layer are formed of different materials from each other and have different multi-thin layer structures from each other.

11. The magnetic memory device of claim 1, wherein the first free magnetic layer is formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof.

12. The magnetic memory device of claim 1, wherein the first free magnetic layer is a multi-thin layer consisting of:

a layer formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Pd, and a mixture thereof; and

a layer consisting of n stacked double layer (n≧

1),

wherein the double layer consists of an X layer and a Y layer, and

wherein the X layer and the Y layer are each independently formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, and Pd.

13. The magnetic memory device of claim 1, wherein the second free magnetic layer is formed of a material selected from a group consisting of Fe, Co, Ni, B, Si, Zr, and a mixture thereof.

14. The magnetic memory device of claim 1 or 2, wherein the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are formed of different materials from each other, and

wherein the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are each independently formed of a material selected from a group consisting of Ru, Cu, Al, Ta, Au, Ag, AlO_x, MgO, TaO_x, ZrO_x, and a mixture thereof.

15. The magnetic memory device of claim 1 or 2, wherein electrical conductivities of the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are higher than those of the first fixed magnetic layer, the first free magnetic layer, the second free magnetic layer and the second fixed magnetic layer.

16. The magnetic memory device of claim 1 or 2, wherein electrical conductivities of the first non-magnetic layer, the second non-magnetic layer and the third non-magnetic layer are lower than those of the first fixed magnetic layer, the first free magnetic layer, the second free magnetic layer and the second fixed magnetic layer.

17. The magnetic memory device of claim 1, further comprising:

an upper electrode and a lower electrode supplying a current to a device.