Magnetic tunnel junction memory devices including crystallized boron-including first magnetic layer on a tunnel barrier layer and lower boron-content second magnetic layer on the first magnetic layer

1. A magnetic memory device, comprising:

a magnetic tunnel junction including a free layer, a pinned layer, and a tunnel barrier layer between the free layer and the pinned layer,

wherein at least one of the free layer and the pinned layer includes,

a first magnetic layer on the tunnel barrier layer and including boron, and

a second magnetic layer on the first magnetic layer and including boron,

wherein the first magnetic layer is crystallized,

wherein a magnetization direction of the first magnetic layer is parallel to a magnetization direction of the second magnetic layer,

wherein the first magnetic layer is between the tunnel barrier layer and the second magnetic layer,

wherein a thickness of the second magnetic layer is thinner than a thickness of the first magnetic layer, and

wherein the second magnetic layer has a lower boron content than the first magnetic layer.

2. The device of claim 1 , wherein a magnetization direction of the free layer is parallel or antiparallel to a magnetization direction of the pinned layer.

3. The device of claim 1 , wherein an atomic percentage of boron in the first magnetic layer is about 20 at %.

4. The device of claim 1 , wherein

the free layer includes the first and second magnetic layers,

the pinned layer includes,

a third magnetic layer on the tunnel barrier layer and including boron, and

a fourth magnetic layer on the third magnetic layer and including boron,

the third magnetic layer is crystallized, and

the third magnetic layer is between the tunnel barrier layer and the fourth magnetic layer.

5. The device of claim 1 , wherein the pinned layer includes the first and second magnetic layers, and

the magnetization direction of the first magnetic layer is parallel to the magnetization direction of the second magnetic layer.

6. A magnetic memory device, comprising:

a magnetic tunnel junction including a free layer, a pinned layer, and a tunnel barrier layer between the free layer and the pinned layer,

wherein at least one of the free layer and the pinned layer includes,

a crystallized first vertical magnetic layer on the tunnel barrier layer and including boron (B), and

a second vertical magnetic layer on the crystallized first vertical magnetic layer and having boron, the second vertical magnetic layer having a lower B content than the crystallized first vertical magnetic layer,

wherein a magnetization direction of the crystallized first magnetic layer is parallel to a magnetization direction of the second vertical magnetic layer,

wherein the crystallized first vertical magnetic layer is between the tunnel barrier layer and the second vertical magnetic layer, and

wherein a thickness of the second vertical magnetic layer is thinner than a thickness of the crystallized first vertical magnetic layer.

7. The device of claim 6 , wherein a value multiplied by a saturation magnetization of the second vertical magnetic layer and the thickness of the second vertical magnetic layer is less than a value multiplied by a saturation magnetization of the crystallized first vertical magnetic layer and the thickness of the crystallized first vertical magnetic layer.

8. The device of claim 6 , wherein

the magnetic tunnel junction is on a substrate; and

the pinned layer is between the substrate and the tunnel barrier layer.

9. The device of claim 6 , wherein

the magnetic tunnel junction is on a substrate; and

the free layer is between the substrate and the tunnel barrier layer.

10. The device of claim 6 , wherein

the pinned layer includes,

a third vertical magnetic layer on the tunnel barrier layer,

a fourth vertical magnetic layer between the third vertical magnetic layer and the tunnel barrier layer, and

an exchange coupled layer between the third vertical magnetic layer and the fourth vertical magnetic layer, and

wherein the fourth vertical magnetic layer includes the crystallized first vertical magnetic layer and the second vertical magnetic layer.

11. The device of claim 6 , wherein one side of the crystallized first vertical magnetic layer contacts one side of the tunnel barrier layer.

12. The device of claim 6 , wherein the second vertical magnetic layer includes at least one of Fe, Co, Ni, Fe including a non-magnetic metal material, Co including the non-magnetic metal material, Ni including the non-magnetic metal material, and alloys thereof.

13. The device of claim 12 , wherein the non-magnetic metal material includes at least one of Ta, Ti, Zr, Hf, B, and Cr.

14. The device of claim 6 , further comprising:

a non-magnetic metal layer between the crystallized first vertical magnetic layer and the second vertical magnetic layer.

15. The device of claim 14 , wherein the non-magnetic metal layer includes at least one of Hf, Zr, Ti, Ta, and alloys thereof.

16. The device of claim 14 , wherein a thickness of the non-magnetic metal layer is less than about 10 Å.

17. The device of claim 6 , further comprising:

a metal oxide layer on the second vertical magnetic layer,

wherein the second vertical magnetic layer is between the metal oxide layer and the tunnel barrier layer.

18. The device of claim 17 , wherein the metal oxide layer includes at least one of a tantalum oxide, a magnesium oxide, a titanium oxide, a zirconium oxide, a hafnium oxide, and a zinc oxide.

19. The device of claim 17 , wherein a resistance of the metal oxide layer is at least ⅓ less than a resistance of the tunnel barrier layer.