Magnetoresistive element and magnetic memory
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.
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.