In recent years, magnetic random access memories (hereinafter abbreviated MRAM), which use a magnetoresistive effect of a ferromagnetic substance, have been attracting attention as next-generation solid-state nonvolatile memories capable of reading and writing data at high speed, offering large-capacity storage, and operating on low power consumption. In particular, magnetoresistive elements including a ferromagnetic tunneling junction have been gaining attention since such magnetoresistive elements were discovered to exhibit a high magnetoresistance rate. A ferromagnetic tunneling junction has a three-layer stacked structure including a storage layer whose magnetization direction is variable, an insulating material layer, and a fixed layer facing the storage layer and maintaining a predetermined magnetization direction.
The magnetoresistive element including a ferromagnetic tunneling junction is also called a magnetic tunnel junction (MTJ) element, and a writing (spin-transfer torque writing) method which uses a spin-momentum transfer (SMT) has been proposed as a writing method thereof. A perpendicular magnetization film, which includes an axis of easy magnetization in a direction perpendicular to a film plane, has been considered to be used as a ferromagnetic material forming the magnetoresistive element.