Magnetic random access memory and method of manufacturing the same
A domain wall motion type MRAM 100 has: a magnetic recording layer 10 that is a ferromagnetic layer; and a magnetic coupling layer 20 that is a ferromagnetic layer whose magnetization direction is fixed. The magnetic recording layer 10 has: a first region 10 - 1 ; a second region 10 - 2 ; and a magnetization switching region 10 - 3 connecting between the first region 10 - 1 and the second region 10 - 2 . The first region 10 - 1 is magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is fixed in a first direction by the magnetic coupling layer 20 . The second region 10 - 2 is not magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is a second direction that is opposite to the first direction.
1. A magnetic random access memory of a domain wall motion type, comprising:
a magnetic recording layer being a ferromagnetic layer and having perpendicular magnetic anisotropy; and
a magnetic coupling layer being a ferromagnetic layer whose magnetization direction is fixed and having perpendicular magnetic anisotropy,
wherein said magnetic recording layer comprises:
a first region that is magnetically coupled to said magnetic coupling layer and whose magnetization direction is fixed in a first direction by said magnetic coupling layer;
a second region that is not magnetically coupled to said magnetic coupling layer and whose magnetization direction is fixed in a second direction opposite to said first direction; and
a magnetization switching region connecting between said first region and said second region,
wherein a cross-sectional area of said second region is larger than a cross-sectional area of said magnetization switching region at a boundary between said second region and said magnetization switching region.
2. The magnetic random access memory according to claim 1 ,
wherein a width of said second region is larger than a width of said magnetization switching region at a boundary between said second region and said magnetization switching region.
3. The magnetic random access memory according to claim 1 ,
wherein a thickness of said second region is larger than a thickness of said magnetization switching region at a boundary between said second region and said magnetization switching region.
4. The magnetic random access memory according to claim 1 , further comprising a nonmagnetic metal layer being in contact with said second region.
5. The magnetic random access memory according to claim 1 ,
wherein when a current flows between said second region and said magnetization switching region, the current density in said second region is lower than the current density in said magnetization switching region.
6. The magnetic random access memory according to claim 1 ,
wherein said magnetic coupling layer is in contact with said first region.
7. The magnetic random access memory according to claim 1 ,
wherein said magnetic coupling layer is connected to at least said first region through an intermediate layer.
8. The magnetic random access memory according to claim 7 ,
wherein said intermediate layer is a nonmagnetic metal layer.
9. The magnetic random access memory according to claim 1 ,
wherein said magnetic recording layer has perpendicular magnetic anisotropy, and
said first direction and said second direction are substantially perpendicular to a plane in which said magnetic recording layer is formed.