Magnetic memory device having an incline side surface
According to one embodiment, a magnetic memory device includes a stacked structure including a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction, and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer. The first magnetic layer includes a first surface in contact with the nonmagnetic layer and a second surface on an opposite side to the first surface, a diameter of the second surface of the first magnetic layer is less than a diameter of the first surface of the first magnetic layer and is 10 nm or more, and a ratio of a height of the first magnetic layer to the diameter of the second surface of the first magnetic layer is 0.9 or more.
1. A magnetic memory device comprising:
a stacked structure comprising:
a first magnetic layer having a variable magnetization direction;
a second magnetic layer having a fixed magnetization direction; and
a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer,
wherein the first magnetic layer includes a first surface in contact with the nonmagnetic layer and a second surface on an opposite side to the first surface,
a diameter of the second surface of the first magnetic layer is less than a diameter of the first surface of the first magnetic layer and is 10 nm or more, and
a ratio of a height of the first magnetic layer to the diameter of the second surface of the first magnetic layer is 0.9 or more.
2. The device of claim 1 , wherein
the diameter of the second surface of the first magnetic layer is 30 nm or less.
3. The device of claim 1 , wherein
a side surface of the first magnetic layer includes a first side-surface portion on a first surface side, a second side-surface portion on a second surface side, and a third side-surface portion between the first side-surface portion and the second side-surface portion, and
inclination of the third side-surface portion is more gentle than inclination of the first side-surface portion and inclination of the second side-surface portion.
4. The device of claim 3 , wherein
a height of a portion of the first magnetic layer, which corresponds to the second side-surface portion is greater than a height of a portion of the first magnetic layer, which corresponds to the first side-surface portion.
5. The device of claim 3 , wherein
a height of a portion of the first magnetic layer, which corresponds to the first side-surface portion is 3 nm or less.
6. The device of claim 1 , wherein
the first magnetic layer contains at least one of iron (Fe) and cobalt (Co).
7. The device of claim 6 , wherein
the first magnetic layer further contains boron (B).
8. The device of claim 1 , wherein
the stacked structure includes the second magnetic layer, the nonmagnetic layer, and the first magnetic layer stacked in an order from a lower layer side.
9. The device of the claim 1 , wherein
the magnetization direction of the first magnetic layer is perpendicular to a main surface thereof, and the magnetization direction of the second magnetic layer is perpendicular to a main surface thereof.
10. A magnetic memory device comprising:
a stacked structure comprising:
a first magnetic layer having a variable magnetization direction;
a second magnetic layer having a fixed magnetization direction; and
a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer,
wherein the first magnetic layer includes a first surface in contact with the nonmagnetic layer and a second surface on an opposite side to the first surface,
a side surface of the first magnetic layer includes a first side-surface portion on a first surface side, a second side-surface portion on a second surface side, and a third side-surface portion between the first side-surface portion and the second side-surface portion, and
inclination of the third side-surface portion is more gentle than inclination of the first side-surface portion and inclination of the second side-surface portion.
11. The device of claim 10 , wherein
a height of a portion of the first magnetic layer, which corresponds to the second side-surface portion is greater than a height of a portion of the first magnetic layer, which corresponds to the first side-surface portion.
12. The device of claim 10 , wherein
a height of a portion of the first magnetic layer, which corresponds to the first side-surface portion is 3 nm or less.
13. The device of claim 10 , wherein
the first magnetic layer contains at least one of iron (Fe) and cobalt (Co).
14. The device of claim 13 , wherein
the first magnetic layer further contains boron (B).
15. The device of claim 10 , wherein
the stacked structure includes the second magnetic layer, the nonmagnetic layer, and the first magnetic layer stacked in an order from a lower layer side.
16. The device of the claim 10 , wherein
the magnetization direction of the first magnetic layer is perpendicular to a main surface thereof, and the magnetization direction of the second magnetic layer is perpendicular to a main surface thereof.