MAGNETORESISTIVE ELEMENT AND MAGNETORESISTIVE RANDOM ACCESS MEMORY INCLUDING THE SAME

• US 20090080124A1
• Filed: 09/15/2008
• Published: 03/26/2009
• Est. Priority Date: 09/25/2007
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nagase, Toshihiko, Yoshikawa, Masatoshi, Yoda, Hiroaki, Kishi, Tatsuya, Daibou, Tadaomi, Kitagawa, Eiji
• Application Number:
  US12/210,496
• Publication Number:
  US 20090080124A1
• Time in Patent Office: Days
• US Class Current: 360/324.120
• 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 11/1659 Cell access
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A magnetoresistive element includes: a first magnetization reference layer having magnetization perpendicular to a film plane, a direction of the magnetization being invariable in one direction; a magnetization free layer having magnetization perpendicular to the film plane, a direction of the magnetization being variable; a first intermediate layer provided between the first magnetization reference layer and the magnetization free layer; a magnetic phase transition layer provided on an opposite side of the magnetization free layer from the first intermediate layer, the magnetic phase transition layer being magnetically coupled to the magnetization free layer, and being capable of bidirectionally performing a magnetic phase transition between an antiferromagnetic material and a ferromagnetic material; and an excitation layer provided on an opposite side of the magnetic phase transition layer from the magnetization free layer, and causing the magnetic phase transition layer to perform the magnetic phase transition from the antiferromagnetic material to the ferromagnetic material.

Claims

1. A magnetoresistive element comprising:

a first magnetization reference layer having magnetization perpendicular to a film plane, a direction of the magnetization being invariable in one direction;

a magnetization free layer having magnetization perpendicular to the film plane, a direction of the magnetization being variable;

a first intermediate layer provided between the first magnetization reference layer and the magnetization free layer;

a magnetic phase transition layer provided on an opposite side of the magnetization free layer from the first intermediate layer, the magnetic phase transition layer being magnetically coupled to the magnetization free layer, and being capable of bidirectionally performing a magnetic phase transition between an antiferromagnetic material and a ferromagnetic material; and

an excitation layer provided on an opposite side of the magnetic phase transition layer from the magnetization free layer, and causing the magnetic phase transition layer to perform the magnetic phase transition from the antiferromagnetic material to the ferromagnetic material,

the magnetization direction of the magnetization free layer being variable by flowing a current between the first magnetization reference layer and the magnetization free layer via the first intermediate layer.

2. The element according to claim 1, wherein:

the magnetic phase transition layer is made of an alloy containing Fe and Rh; and

the magnetic phase transition layer is expressed as Fe<sub>1−

x</sub>Rh_x (0.3≦

x≦

0.7), which indicates relative proportions of Fe and Rh.

3. The element according to claim 1, wherein the magnetic phase transition layer is made of an alloy containing Fe, Rh, and at least one element A selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Ru, Pd, Ag, Os, Ir, Pt, and Au, and is expressed as Fe₁₋

x(Rh<sub>1−

y</sub>A_y)_x (0.3≦

x≦

0.7, 0<

y<

1), which indicates relative proportions of Fe, Rh, and the element represented by “

A”

.

4. The element according to claim 1, wherein the magnetization free layer is a ferromagnetic film or a ferromagnetic film that contains 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.

5. The element according to claim 4, wherein the magnetization free layer has a face-centered tetragonal structure, and has a L1₀ ordered structure phase.

6. The element according to claim 5, wherein the magnetization free layer is orientated to the (001) plane.

7. The element according to claim 1, wherein the excitation layer is made of a material having specific resistance of 200 μ

Ω

cm or higher.

8. The element according to claim 1, wherein the magnetization direction of the magnetization free layer is variable by bidirectionally flowing the current between the first magnetization reference layer and the excitation layer via the phase transition layer.

17. A magnetoresistive random access memory comprising

the magnetoresistive element according to claim 1 as a memory cell.

18. A magnetoresistive random access memory comprising:

a memory cell including the magnetoresistive element according to claim 1 and a transistor having one end series-connected to one end of the magnetoresistive element;

a first write current circuit connected to the other end of the magnetoresistive element; and

a second write current circuit connected to the other end of the transistor, and, in cooperation with the first write current circuit, flowing the current between the first magnetization reference layer and the excitation layer via the magnetic phase transition layer.

9. A magnetoresistive element comprising:

a first magnetization reference layer having magnetization perpendicular to a film plane, a direction of the magnetization being invariable in one direction;

a magnetization free layer having magnetization perpendicular to the film plane, a direction of the magnetization being variable;

a first intermediate layer provided between the first magnetization reference layer and the magnetization free layer;

a magnetic phase transition layer provided on an opposite side of the magnetization free layer from the first intermediate layer, the magnetic phase transition layer being magnetically coupled to the magnetization free layer, and being capable of bidirectionally performing a magnetic phase transition between an antiferromagnetic material and a ferromagnetic material;

a second magnetization reference layer provided on an opposite side of the magnetic phase transition layer from the magnetization free layer, the second magnetization reference layer having magnetization perpendicular to the film plane, a direction of the magnetization being invariable in one direction and being antiparallel to the magnetization direction of the first magnetization reference layer;

a second intermediate layer provided between the magnetic phase transition layer and the second magnetization reference layer, and causing the magnetic phase transition layer to perform the magnetic phase transition from the antiferromagnetic material to the ferromagnetic material,

the magnetization direction of the magnetization free layer being variable by flowing a current between the first magnetization reference layer and the magnetization free layer via the first intermediate layer.

10. The element according to claim 9, wherein:

the magnetic phase transition layer is made of an alloy containing Fe and Rh; and

the magnetic phase transition layer is expressed as Fe<sub>1−

x</sub>Rh_x (0.3≦

x≦

0.7), which indicates relative proportions of Fe and Rh.

11. The element according to claim 9, wherein the magnetic phase transition layer is made of an alloy containing Fe, Rh, and at least one element A selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Ru, Pd, Ag, Os, Ir, Pt, and Au, and is expressed as Fe₁₋

x(Rh<sub>1−

y</sub>A_y)_x (0.3≦

x≦

0.7, 0<

y<

1), which indicates relative proportions of Fe, Rh, and the element represented by “

A”

.

12. The element according to claim 9, wherein the magnetization free layer is a ferromagnetic film or a ferrimagnetic film that contains 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.

13. The element according to claim 12, wherein the magnetization free layer has a face-centered tetragonal structure, and has a L1₀ ordered structure phase.

14. The element according to claim 13, wherein the magnetization free layer is orientated to the (001) plane.

15. The element according to claim 9, wherein the excitation layer is made of a material having specific resistance of 200 μ

Ω

cm or higher.

16. The element according to claim 9, wherein the magnetization direction of the magnetization free layer is variable by bidirectionally flowing the current between the first magnetization reference layer and the second magnetization reference layer via the second intermediate layer.

19. A magnetoresistive random access memory comprising

the magnetoresistive element according to claim 9 as a memory cell.

20. A magnetoresistive random access memory comprising:

a memory cell including the magnetoresistive element according to claim 9 and a transistor having one end series-connected to one end of the magnetoresistive element;

a first write current circuit connected to the other end of the magnetoresistive element; and

a second write current circuit connected to the other end of the transistor, and, in cooperation with the first write current circuit, flowing the current between the first magnetization reference layer and the second magnetization reference layer via the second intermediate layer.