The ferromagnet 43 either contains or is made of, for example, cobalt iron boron (CoFeB) or iron boride (FeB). The ferromagnet 43 has an easy magnetization axis along a direction (indicated by an arrow in the ferromagnet 43) penetrating interfaces between the ferromagnet 41, insulator 42, and ferromagnet 43, such as an easy magnetization axis at an angle from 45° to 90° with respect to the interfaces, or an easy magnetization axis along a direction orthogonal to the interfaces. The magnetization direction of ferromagnet 43 can be changed by data writing, and the ferromagnet 43 can function as a so-called “storage layer”.

When the magnetization direction of ferromagnet 43 is parallel to the magnetization direction of ferromagnet 41, the variable resistance element VR is in a lower resistance state. When the magnetization direction of ferromagnet 43 is anti-parallel to the magnetization direction of ferromagnet 41, the variable resistance element VR is in a higher resistance state.

When a certain magnitude of write current flows from the ferromagnet 43 to the ferromagnet 41, the magnetization direction of ferromagnet 43 becomes parallel to the magnetization direction of ferromagnet 41. In contrast, when another magnitude of write current flows from the ferromagnet 41 to the ferromagnet 43, the magnetization direction of ferromagnet 43 becomes anti-parallel to the magnetization direction of ferromagnet 41.

The hard mask 44 is made of a conductor. Inter-layer insulators (not shown) are provided on the portions other than the components shown in FIG. 4.

<1.5. Dopant Concentration Distribution in Variable Resistance Material>