Magnetoresistive element

• US 7,663,197 B2
• Filed: 09/22/2006
• Issued: 02/16/2010
• Est. Priority Date: 10/19/2005
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nagase, Toshihiko, Nakayama, Masahiko, Yoshikawa, Masatoshi, Kishi, Tatsuya, Kai, Tadashi, Yoda, Hiroaki, Kitagawa, Eiji
• Primary Examiner(s): Wilson; Allan R.
• Application Number:
  US11/534,440
• Publication Number:
  US 20070086121A1
• Time in Patent Office: 1,243 Days
• Field of Search: 257/421, 257/422, 257/E27.006, 360/324
• US Class Current: 257/421
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• 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 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0≧Ms<√{square root over ( )}{Jw/(6πAt)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.

Claims

1. A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, comprising:

a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface;

a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons;

a first nonmagnetic layer which is provided between the first pinned layer and the free layer;

a first magnetic metal layer which is provided between the first pinned layer and the first nonmagnetic layer and contains at least one element selected from the group consisting of Fe, Co, and Ni; and

a second magnetic metal layer which is provided between the free layer and the first nonmagnetic layer and contains at least one element selected from the group consisting of Fe, Co, and Ni;

wherein

the first nonmagnetic layer essentially consists of MgO with a (001) plane being oriented, and

at least one of the first magnetic metal layer and the second magnetic metal layer is made of a magnetic material selected from the group consisting of Co, Fe, Co—

Fe alloy, and Fe—

Ni alloy having a bcc structure and a (001) plane oriented, and the magnetic material of at least one of the first pinned layer and the free layer comprises an L1₀ ordered alloy with a (001) plane being oriented.

2. The element according to claim 1, further comprising:

a second pinned layer which is made of a magnetic material and has a third magnetization directed in the direction perpendicular to the film surface; and

a second nonmagnetic layer which is provided between the second pinned layer and the free layer.

3. The element according to claim 1, which further comprises:

a second pinned layer which is made of a magnetic material and has a third magnetization directed in the direction perpendicular to the film surface; and

a second nonmagnetic layer which is provided between the second pinned layer and the free layer; and

in which a first magnetoresistive ratio generated between the free layer and the first pinned layer through the first nonmagnetic layer is larger than a second magnetoresistive ratio generated between the free layer and the second pinned layer through the second nonmagnetic layer.

4. The element according to claim 1, wherein

at least one of the layers made of the magnetic material comprises a first magnetic layer, a second magnetic layer, and a third nonmagnetic layer which is provided between the first magnetic layer and the second magnetic layer, and

the first magnetic layer and the second magnetic layer are antiferromagnetically coupled to each other.

5. The element according to claim 1, wherein

at least one of the layers made of the magnetic material comprises a first magnetic layer and a second magnetic layer,

the first magnetic layer is made of a ferrimagnetic material containing an alloy of a first rare-earth metal and a first transition metal, and the second magnetic layer is made of a ferrimagnetic material containing an alloy of a second rare-earth metal and a second transition metal, and

a magnetic moment of the first rare-earth metal is larger than a magnetic moment of the first transition metal, a magnetic moment of the second transition metal is larger than a magnetic moment of the second rare-earth metal, and the first magnetic layer and the second magnetic layer are antiferromagnetically coupled to each other.

6. The element according to claim 1, wherein

at least one of the layers made of the magnetic material comprises a first magnetic layer, a second magnetic layer, and a third nonmagnetic layer which is provided between the first magnetic layer and the second magnetic layer,

the first magnetic layer is made of a ferrimagnetic material containing an alloy of a first rare-earth metal and a first transition metal, and the second magnetic layer is made of a ferrimagnetic material containing an alloy of a second rare-earth metal and a second transition metal,

when the third nonmagnetic layer is made of a material that antiferromagnetically couples the first transition metal to the second transition metal, a magnetization of the first magnetic layer and a magnetization of the second magnetic layer are arranged antiparallel by making a magnitude relationship between a magnetic moment of the first rare-earth metal and a magnetic moment of the first transition metal equal to a magnitude relationship between a magnetic moment of the second rare-earth metal and a magnetic moment of the second transition metal, and

when the third nonmagnetic layer is made of a material that ferromagnetically couples the first transition metal to the second transition metal, the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are arranged antiparallel by making the magnitude relationship between the magnetic moment of the first rare-earth metal and the magnetic moment of the first transition metal different from the magnitude relationship between the magnetic moment of the second rare-earth metal and the magnetic moment of the second transition metal.

7. The element according to claim 1, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

8. The element according to claim 1, wherein at least one of the layers made of the magnetic material is made of an alloy having Co as a principal component and containing at least one element selected from the group consisting of Cr, Ta, Nb, V, W, Hf, Ti, Zr, Pt, Pd, Fe, and Ni.

9. The element according to claim 8, wherein

the first nonmagnetic layer essentially consists of MgO with a (001) plane being oriented, and

at least one of the first magnetic metal layer and the second magnetic metal layer is made of a magnetic material selected from the group consisting of Co, Fe, Co—

Fe alloy, and Fe—

Ni alloy having a bcc structure and a (001) plane oriented.

10. The element according to claim 1, wherein at least one of the layers made of the magnetic material is made of an alloy containing at least one element selected from the group consisting of Fe, Co, and Ni and at least one element selected from the group consisting of Pt and Pd, the alloy being an ordered alloy with an L10 crystal structure.

11. The element according to claim 8, wherein

the first nonmagnetic layer essentially consists of MgO with a (001) plane being oriented, and

at least one of the first magnetic metal layer and the second magnetic metal layer is made of a magnetic material selected from the group consisting of Co, Fe, Co—

Fe alloy, and Fe—

Ni alloy having a bcc structure and a (001) plane oriented.

12. The element according to claim 1, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

13. The element according to claim 8, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

14. The element according to claim 9, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

15. The element according to claim 10, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

16. The element according to claim 11, wherein the second magnetic metal layer is thinner than the first magnetic metal layer.

17. The element according to claim 1, wherein the second magnetic metal layer is thinner than the free layer and the first magnetic metal layer is thinner than the first pinned layer.

18. The element according to claim 8, wherein the second magnetic metal layer is thinner than the free layer and the first magnetic metal layer is thinner than the first pinned layer.

19. The element according to claim 9, wherein the second magnetic metal layer is thinner than the free layer and the first magnetic metal layer is thinner than the first pinned layer.

20. The element according to claim 10, wherein the second magnetic metal layer is thinner than the free layer and the first magnetic metal layer is thinner than the first pinned layer.

21. The element according to claim 11, wherein the second magnetic metal layer is thinner than the free layer and the first magnetic metal layer is thinner than the first pinned layer.