Magnetoresistive element and memory device

1. A magnetoresistive element comprising:

a first metal layer having a body-centered cubic structure;

a second metal layer having a hexagonal close-packed structure on the first metal layer;

a metal nitride layer on the second metal layer;

a first magnetic layer on the metal nitride layer;

an insulating layer on the first magnetic layer; and

a second magnetic layer on the insulating layer.

2. The magnetoresistive element of claim 1 , wherein the first metal layer comprises one of Nb, Mo, Ta, Cr and V.

3. The magnetoresistive element of claim 1 , wherein the second metal layer comprises one of Hf, Sc, Y and Zr.

4. The magnetoresistive element of claim 1 , wherein:

the metal nitride layer comprises a nitrogen compound or a mixture of the nitrogen compound and an oxygen compound,

the nitrogen compound comprises magnesium nitride, zirconium nitride, niobium nitride, silicon nitride, aluminum nitride, hafnium nitride, tantalum nitride, tungsten nitride, chromium nitride, molybdenum nitride, titanium nitride, or vanadium nitride, and

the oxygen compound comprises magnesium oxide.

5. The magnetoresistive element of claim 1 , wherein each of the first and second magnetic layers comprises Co and Fe, and the insulating layer comprises magnesium oxide.

6. The magnetoresistive element of claim 3 , wherein:

each of the first and second magnetic layers has a body-centered cubic structure in which a film surface is orientated in a (001)-surface, and

the insulating layer has an NaCl structure in which a film surface is orientated in a (001)-surface.

7. The magnetoresistive element of claim 1 , wherein the first metal layer has a thickness of 0.5 nm or more and 4.5 nm or less.

8. The magnetoresistive element of claim 1 , wherein the second metal layer has a thickness of 2 nm or more and 20 nm or less.

9. The magnetoresistive element of claim 1 , wherein the metal nitride layer has a thickness of 0.4 nm or more and 2 nm or less.

10. The magnetoresistive element of claim 1 , wherein the metal nitride layer has a hexagonal close-packed structure.

11. The magnetoresistive element of claim 1 , wherein the first magnetic layer has variable magnetization direction, and the second magnetic layer has invariable magnetization direction.

12. The magnetoresistive element of claim 11 , further comprising:

a third metal layer on the second magnetic layer; and

a third magnetic layer having invariable magnetization on the third metal layer,

wherein the second and third magnetic layers are SAF-coupled to each other.

13. The magnetoresistive element of claim 1 , further comprising:

a third metal layer under the first metal layer,

wherein the third metal layer has a crystal structure or an amorphous structure.

14. The magnetoresistive element of claim 1 , wherein each of the first and second magnetic layers has an axis of easy magnetization in a direction perpendicular to a film surface.

15. The magnetoresistive element of claim 1 , wherein each of the first and second magnetic layers includes an element selected from a group of Mo, W, Ta, Zr, Hf, Cr and V.

16. A memory device comprising:

a semiconductor substrate;

a select transistor on the semiconductor substrate; and

the magnetoresistive element of claim 1 above the select transistor, the magnetoresistive element being connected to the select transistor.

17. A magnetoresistive element comprising:

a first metal layer comprising one of Nb, Mo, Ta, Cr and V, and having a body-centered cubic structure;

a second metal layer on the first metal layer, the second metal layer comprising one of Hf, Sc, Y and Zr, and having a hexagonal close-packed structure, wherein the second metal layer is in direct contact with the first metal layer;

an aluminum nitride layer on the second metal layer;

a first magnetic layer on the aluminum nitride layer;

an insulating layer on the first magnetic layer; and

a second magnetic layer on the insulating layer.