Magnetic random access memory and write method of the same

1. A magnetic random access memory comprising:

a magnetoresistive effect element which includes a fixed layer in which a magnetization direction is fixed, a recording layer in which a magnetization direction is reversible, and a nonmagnetic layer formed between the fixed layer and the recording layer, and in which the magnetization directions in the fixed layer and the recording layer take one of a parallel state and an antiparallel state in accordance with a direction of an electric current supplied between the fixed layer and the recording layer; and

a yoke layer which concentrates a magnetic field generated by the electric current, and causes the magnetic field to act on magnetization in the recording layer, the yoke layer not being formed above an upper surface or below a bottom surface of the magnetoresistive effect element.

2. The memory according to claim 1 , wherein the yoke layer surrounds a circumferential surface of the magnetoresistive effect element.

3. The memory according to claim 1 , wherein the yoke layer has a slit around the recording layer.

4. The memory according to claim 1 , wherein an end portion of the yoke layer is positioned between an upper surface and bottom surface of the recording layer.

5. The memory according to claim 1 , wherein a bottom surface of the yoke layer is positioned between an upper surface and bottom surface of the recording layer.

6. The memory according to claim 1 , wherein an upper surface of the yoke layer is positioned between an upper surface and bottom surface of the recording layer.

7. The memory according to claim 6 , which further comprises an interconnection formed below the magnetoresistive effect element, and

in which the yoke layer is formed around the interconnection.

8. The memory according to claim 1 , which further comprises a contact connected to the recording layer and in contact with the recording layer by an area smaller than an area of the recording layer, and

in which the yoke layer surrounds the magnetoresistive effect element.

9. The memory according to claim 1 , which further comprises a contact connected to the recording layer and in contact with the recording layer by an area smaller than an area of the recording layer, and

in which the yoke layer surrounds the contact.

10. The memory according to claim 1 , wherein

the magnetoresistive effect element and the yoke layer have a ring-like shape, and

the yoke layer comprises a first portion formed inside the magnetoresistive effect element, and a second portion formed outside the magnetoresistive effect element.

11. The memory according to claim 1 , which further comprises a contact connected to the recording layer and in contact with the recording layer by an area smaller than an area of the recording layer, and

in which an upper surface of the yoke layer is positioned around the fixed layer.

12. The memory according to claim 1 , wherein the yoke layer surrounds a circumferential surface of the magnetoresistive effect element, and has slits at two ends in an easy magnetization axis direction of the magnetoresistive effect element.

13. The memory according to claim 12 , wherein the slits are formed perpendicularly to a film surface of the magnetoresistive effect element.

14. The memory according to claim 12 , wherein the slits have an elliptic shape extending perpendicularly to a film surface of the magnetoresistive effect element.

15. The memory according to claim 12 , wherein the slits are formed obliquely to a film surface of the magnetoresistive effect element.