Magnetic random access memories (MRAMs) in which the magnetoresistive effect of a ferromagnetic material is used have recently attracted interest as next-generation solid-state nonvolatile memories capable of speeding up read/write operations, increasing capacity, and realizing low-power operation. In particular, magnetoresistive elements including a ferromagnetic tunnel junction have received a great deal of attention since the finding of the ability of exhibiting a high rate of magnetoresistive change. The ferromagnetic tunnel junction has a three-layer structure including a storage layer having a variable magnetization direction, an insulating layer, and a fixed layer that faces the storage layer and maintains a predetermined magnetization direction.
A magnetoresistive element having the ferromagnetic tunnel junction is also called a magnetic tunnel junction (MTJ) element. A write method (spin transfer torque writing) using spin-momentum transfer (SMT) has been proposed for this magnetoresistive element.