Magneto-resistive element

• US 20050219767A1
• Filed: 03/24/2005
• Published: 10/06/2005
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakamura, Shiho, Haneda, Shigeru
• Granted Patent: US 7,561,385 B2
• Time in Patent Office: Days
• US Class Current: 360/324.100
• CPC Class Codes: G11B 5/39 using magneto-resistive devices or effects
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magneto-resistive element comprising a free layer having two ferromagnetic layers having a nonmagnetic layer interposed therebetween are coupled with each other in an anti-ferromagnetic manner, a difference between an absolute value of a total of magnetizations of at least one ferromagnetic layer in which the magnetization direction is a first direction and an absolute value of a total of magnetizations of at least one ferromagnetic layer in which the magnetization direction is a second direction which is opposite to the first direction is equal to or smaller than 5×10⁻¹⁵ emu, and planes parallel to a substrate of the ferromagnetic layers are smaller as the planes are distant from the substrate.

Claims

1. A magneto-resistive element comprising:

a fixed layer in which a magnetization direction is fixed;

a free layer in which the magnetization direction is changed by spin-polarized electrons, the free layer having ferromagnetic layers separated by a non-magnetic layer, wherein, from among the ferromagnetic layers, the two adjacent ferromagnetic layers having the nonmagnetic layer interposed therebetween are coupled with each other in an anti-ferromagnetic manner;

from among the ferromagnetic layers, a difference between an absolute value of a total of magnetizations of at least one ferromagnetic layer in which the magnetization direction is a first direction and an absolute value of a total of magnetizations of at least one ferromagnetic layer in which the magnetization direction is a second direction which is opposite to the first direction is equal to or smaller than 5×

10<sup>−

15</sup> emu; and

planes parallel to a substrate of the ferromagnetic layers are smaller as the planes are distant from the substrate; and

an intermediate layer between the fixed layer and the free layer.

2. The magneto-resistive element according to claim 1, wherein the magnetization of each of the ferromagnetic layers is determined by a product between a magnetization per unit volume and a volume of the layer.

3. The magneto-resistive element according to claim 1, wherein, from among the ferromagnetic layers, a thickness of a ferromagnetic layer which is the most distant from the substrate is greater than a thickness of a ferromagnetic layer which is the most proximal to the substrate.

4. The magneto-resistive element according to claim 1, wherein a sectional plane in a direction vertical to the substrate of the free layer is formed in a trapezoidal shape.

5. The magneto-resistive element according to claim 4, wherein a side face of the free layer has an angle of 30°

or more and 85°

or less with respect to the substrate.

6. The magneto-resistive element according to claim 1, wherein a magnetic yoke is allocated via an insulating layer on a side face of the free layer.

7. The magneto-resistive element according to claim 1, wherein a magneto-resistive effect produced by the fixed layer, the free layer, and the intermediate layer is one of a normal type and a reverse type.

8. The magneto-resistive element according to claim 1, wherein the intermediate layer has an insulator, a semiconductor, an electrical conductor, and a pin hole, and is composed of one of the insulators filled with the electrical conductor including a magnetic body in the pin hole.

9. The magneto-resistive element according to claim 1, wherein the fixed layer has ferromagnetic layers separated by a non-magnetic layer, and the two adjacent ferromagnetic layers having the nonmagnetic layer interposed therebetween are coupled with each other in an anti-ferromagnetic manner.

10. A magneto-resistive element comprising:

first and second fixed layers in which a magneti-zation direction is fixed;

a free layer which is allocated between the first and second fixed layers, and in which the magnetization direction is changed by spin-polarized electrons, the free layer having ferromagnetic layers separated by a nonmagnetic layer, wherein, from among the ferromagnetic layers, the two adjacent ferromagnetic layers having the nonmagnetic layer interposed therebetween are coupled with each other in an anti-ferromagnetic manner;

from among the ferromagnetic layers, a difference between an absolute value of a total of magnetizations of at least one ferromagnetic layer in which the magnetization direction is a first direction and an absolute value of a total of magneti-zations of at least one ferromagnetic layer in which the magnetization direction is a second direction which is opposite to the first direction is equal to or smaller than 5×

10<sup>−

15</sup> emu; and

planes parallel to a substrate of the ferromagnetic layers are smaller as the planes are distant from the substrate;

a first intermediate layer between the first fixed layer and the free layer; and

a second intermediate layer between the second fixed layer and the free layer.

11. The magneto-resistive element according to claim 10, wherein the magnetization of each of the ferromagnetic layers is determined by a product between a magnetization per unit volume and a volume of the layer.

12. The magneto-resistive element according to claim 11, wherein, from among the ferromagnetic layers, a thickness of a ferromagnetic layer which is the most distant from the substrate is greater than a thickness of a ferromagnetic layer which is the most proximal to the substrate.

13. The magneto-resistive element according to claim 10, wherein a sectional plane in a direction vertical to the substrate of the free layer is formed in a trapezoidal shape.

14. The magneto-resistive element according to claim 13, wherein a side face of the free layer has an angle of 30°

or more and 85°

or less with respect to the substrate.

15. The magneto-resistive element according to claim 10, wherein a magnetic yoke is allocated via an insulating layer on the side face of the free layer.

16. The magneto-resistive element according to claim 10, wherein a magneto-resistive effect produced by the first and second fixed layers, the free layer, and the first and second intermediate layers is one of a normal type and a reverse type.

17. The magneto-resistive element according to claim 10, wherein, in the case where magnetization states of the first and second fixed layers are identical to each other, the first and second intermediate layers are composed of different materials.

18. The magneto-resistive element according to claim 10, wherein, in the case where magnetization states of the first and second fixed layers are different from each other, the first and second intermediate layers are composed of an identical material.

19. The magneto-resistive element according to claim 10, wherein the first and second intermediate layers each have an insulator, a semiconductor, an electrical conductor, and a pin hole, and are composed of one of the insulators filled with the electrical conductor including a magnetic body in the pin hole.

20. The magneto-resistive element according to claim 10, wherein the fixed layer has ferromagnetic layers separated by a non-magnetic layer, and the two adjacent ferromagnetic layers having the nonmagnetic layer interposed therebetween are coupled with each other in an anti-ferromagnetic manner.