Magnetoresistive element and magnetic memory

• US 9,450,177 B2
• Filed: 02/14/2011
• Issued: 09/20/2016
• Est. Priority Date: 03/10/2010
• Status: Active Grant

• Current Assignee: Tohoku University National Universities Corporation
• Original Assignee: Tohoku University National Universities Corporation
• Inventors: Ohno, Hideo, Ikeda, Shoji, Matsukura, Fumihiro, Endoh, Masaki, Kanai, Shun, Miura, Katsuya, Yamamoto, Hiroyuki
• Primary Examiner(s): Hoang, Huan
• Assistant Examiner(s): Radke, Jay
• Application Number:
  US13/578,866
• Publication Number:
  US 20120320666A1
• Time in Patent Office: 2,045 Days
• Field of Search: 365/158, 365/171, 365/158.171
• US Class Current: 1/1
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

There is provided a magnetoresistive element whose magnetization direction is stable in a direction perpendicular to the film surface and whose magnetoresistance ratio is controlled, as well as magnetic memory using such a magnetoresistive element. By having the material of a ferromagnetic layer forming the magnetoresistive element comprise a ferromagnetic material containing at least one type of 3d transition metal, or a Heusler alloy, to control the magnetoresistance ratio, and by controlling the thickness of the ferromagnetic layer on an atomic layer level, the magnetization direction is changed from being in-plane with the film surface to being perpendicular to the film surface.

Claims

1. A magnetoresistive element comprising:

a reference layer having a fixed magnetization direction and including a ferromagnetic material containing Fe;

one non-magnetic layer that is directly formed on one surface of the reference layer and that includes an insulator containing oxygen;

a recording layer that is directly formed on one surface of the one non-magnetic layer, which is opposite to another surface on which the reference layer is formed, the recording layer having a variable magnetization direction and including a ferromagnetic material containing at least one type of 3d transition metal; and

another non-magnetic layer that is directly formed on another surface of the reference layer so that the reference layer is formed between the one and the other non-magnetic layers and the one and the other non-magnetic layers are both external to the reference layer, the other non-magnetic layer including an insulator containing oxygen, wherein

the reference layer, and the one and the other non-magnetic layers are arranged so that a magnetization direction of the reference layer is controlled to be perpendicular to a layer surface of the reference layer by perpendicular magnetic anisotropy at interfaces between the reference layer and the one non-magnetic layer, and between the reference layer and the other non-magnetic layer, resulting from the reference layer having a predetermined thickness, and

the other non-magnetic layer stabilizes the perpendicularity of magnetization direction of the reference layer to the reference layer surface.

2. The magnetoresistive element according to claim 1, wherein the predetermined thickness of the reference layer is equal to or less than 3 nm.

3. The magnetoresistive element according to claim 1, wherein the reference layer further includes at least one of Co and B.

4. The magnetoresistive element according to claim 1, wherein the one and the other non-magnetic layers further include Mg.

5. The magnetoresistive element according to claim 1, further comprising an additional non-magnetic layer that is directly formed on one surface of the recording layer, which is opposite to another surface on which the one non-magnetic layer is formed on and that includes an insulator containing oxygen.

6. The magnetoresistive element according to claim 5, wherein the additional non-magnetic layer further includes Mg.

7. The magnetoresistive element according to claim 1, wherein

the reference layer has a laminate structure including a plurality of alternating ferromagnetic and non-magnetic laminated layers,

uppermost and lowermost layers of the laminate structure are the ferromagnetic laminated layers, and

the ferromagnetic laminated layer includes a ferromagnetic material containing Fe, and the non-magnetic laminated layer includes an insulator containing oxygen.

8. The magnetoresistive element according to claim 7, wherein the ferromagnetic laminated layer further includes at least one of Co and B, and the non-magnetic laminated layer further includes Mg.

9. A magnetoresistive element comprising:

a reference layer having a fixed magnetization direction and including a ferromagnetic material containing at least one type of 3d transition metal;

one non-magnetic layer that is directly formed on one surface of the reference layer and that includes an insulator containing oxygen;

a recording layer that is directly formed on one surface of the one non-magnetic layer, which is opposite to another surface on which the reference layer is formed, the recording layer having a variable magnetization direction and including a ferromagnetic material containing Fe; and

another non-magnetic layer that is directly formed on one surface of the recording layer, which is opposite to another surface on which the one non-magnetic layer is formed, so that the recording layer is formed between the one and the other non-magnetic layers and the one and the other non-magnetic layers are both external to the recording layer, the other non-magnetic layer including an insulator containing oxygen, wherein

the recording layer, and the one and the other non-magnetic layers are arranged so that a magnetization direction of the recording layer is controlled to be perpendicular to a layer surface of the recording layer by perpendicular magnetic anisotropy at interfaces between the recording layer and the one non-magnetic layer, and between the recording layer and the other non-magnetic layer, resulting from the recording layer having a predetermined thickness, and

the other non-magnetic layer stabilizes the perpendicularity of magnetization direction of the recording layer to the recording layer surface.

10. The magnetoresistive element according to claim 9, wherein the predetermined thickness of the recording layer is equal to or less than 3 nm.

11. The magnetoresistive element according to claim 9, wherein the recording layer further includes at least one of Co and B.

12. The magnetoresistive element according to claim 9, wherein the one and the other non-magnetic layers further include Mg.

13. The magnetoresistive element according to claim 9, wherein

the recording layer has a laminate structure including a plurality of alternating ferromagnetic and non-magnetic laminated layers,

uppermost and lowermost layers of the laminate structure are the ferromagnetic laminated layers, and

the ferromagnetic laminated layer includes a ferromagnetic material containing Fe, and the non-magnetic laminated layer includes an insulator containing oxygen.