Magnetic tunnel junction including a free layer structure and magnetic memory device comprising the same

Patent metadata

Field	Value
Publication number	US-11088319-B2
Application number	US-201916685415-A
Country	US
Kind code	B2
Filing date	Nov 15, 2019
Priority date	Feb 1, 2019
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

In one embodiment, the magnetic memory device includes a free layer structure having a variable magnetization direction. The free layer structure includes a first free layer, the first free layer being a first Heusler alloy; a coupling layer on the first free layer, the coupling layer including a metal oxide layer; and a second free layer on the metal oxide layer, the second free layer being a second Heusler alloy, the second Heusler alloy being different from the first Heusler alloy.

First claim

What is claimed is:

1. A magnetic memory device, comprising:
a free layer structure having a variable magnetization direction, the free layer structure including,
a first free layer, the first free layer being a first Heusler alloy,
a coupling layer on the first free layer, the coupling layer including a metal oxide layer, the coupling layer configured to induce a perpendicular magnetic anisotropy in the first free layer, and
a second free layer on the metal oxide layer, the second free layer being a second Heusler alloy, the second Heusler alloy being different from the first Heusler alloy;

a pinned layer structure, the pinned layer structure having a fixed magnetization direction; and
a tunnel barrier layer between the pinned layer structure and the free layer structure.

2. The magnetic memory device of claim 1 , wherein a magnetic coupling strength between the first free layer and the second free layer is 0.05-1 erg/cm2.

3. The magnetic memory device of claim 2 , wherein a thickness of the metal oxide layer is less than or equal to 1.5 nm.

4. The magnetic memory device of claim 3 , wherein the metal oxide layer includes Mg, Al, Hf, Zr, Ta, Nb or combinations thereof.

5. The magnetic memory device of claim 1 , wherein a thickness of the metal oxide layer is less than or equal to 1.5 nm.

6. The magnetic memory device of claim 5 , wherein the metal oxide layer includes Mg, Al, Hf, Zr, Ta, Nb or combinations thereof.

7. The magnetic memory device of claim 1 , wherein the first free layer has a cubic structure.

8. The magnetic memory device of claim 1 , wherein the first free layer has a saturation magnetization of 1200 emu/cc or less.

9. The magnetic memory device of claim 1 , wherein the first free layer has a saturation magnetization of 500-1200 emu/cc.

10. The magnetic memory device of claim 1 , wherein the first free layer has a tunneling magnetoresistance ratio at room temperature of greater than 100%.

11. The magnetic memory device of claim 1 , wherein the first free layer has thickness of 5 nm or less.

12. The magnetic memory device of claim 1 , wherein the first free layer has the structure X2YZ, where X═Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ad, Cd, Ir, Pt, Au, or Mg; Y═Be, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Nb, Mo, Hf, W, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu; and Z═Mg, B, Al, Si, Zn, Ga, Ge, As, In, Sn, Sb, Pb, or Bi.

13. The magnetic memory device of claim 1 , wherein the first free layer includes cobalt.

14. The magnetic memory device of claim 1 , wherein the second free layer has a tetragonal structure.

15. The magnetic memory device of claim 1 , wherein the second free layer has a saturation magnetization of less than or equal to 500 emu/cc.

16. The magnetic memory device of claim 1 , wherein the second free layer has a thickness of 10 nm or less.

17. The magnetic memory device of claim 1 , wherein the second free layer includes one of cobalt, nickel, iron, manganese or a combination thereof.

18. The magnetic memory device of claim 17 , wherein the second free layer is Mn3X, where X═Ge, Ga, Sb, Al, or combinations thereof.

19. A magnetic memory device, comprising:
a pinned layer structure, the pinned layer structure having a fixed magnetization direction, the pinned layer structure including,
a first pinned layer,
a non-magnetic layer, and
a second pinned layer, the first pinned layer and the second pinned layer having anti-parallel magnetization directions;

a free layer structure having a variable magnetization direction, the free layer structure including,
a first free layer, the first free layer being a first Heusler alloy, having a cubic structure, and having a first saturation magnetization,
a metal oxide layer on the first free layer, and
a second free layer on the metal oxide layer, the second free layer being a second Heusler alloy having a tetragonal structure and having a second saturation magnetization, the second saturation magnetization being less than the first saturation magnetization, and a magnetic coupling strength between the first free layer and second free layer is 0.05-1 erg/cm2; and
a tunnel barrier layer between the pinned layer structure and the free layer structure.

20. A magnetic memory device, comprising:
a free layer structure having a variable magnetization direction, the free layer structure including,
a first free layer, the first free layer being a first Heusler alloy,
a coupling layer on the first free layer, the coupling layer including a metal oxide layer, and
a second free layer on the metal oxide layer, the second free layer being a second Heusler alloy, the second Heusler alloy being different from the first Heusler alloy;

a pinned layer structure, the pinned layer structure having a fixed magnetization direction; and
a tunnel barrier layer between the pinned layer structure and the free layer structure,
wherein a magnetic coupling strength between the first free layer and the second free layer is 0.05-1 erg/cm2.

Assignees

• Samsung Electronics Co Ltd

Inventors

• Kim Kwang Seok
• Jang Young Man
• Pi Ung Hwan

Classifications

• H01F10/3272

  by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets · CPC title

• H01F10/1936

  Half-metallic, e.g. epitaxial CrO2 or NiMnSb films · CPC title

• G11C11/1675

  Writing or programming circuits or methods · CPC title

• G11C11/1659

  Cell access · CPC title

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title