MAGNETIC MEMORY DEVICE
According to one embodiment, a magnetic memory device includes a stacked structure including a first layer having a variable magnetization direction, a second layer having a fixed magnetization direction, a third layer between the first and second layers, adjacent to the first main surface of the first layer and the first main surface of the second layer, and functioning as a tunnel barrier, and a conductive fourth layer including a first main surface adjacent to the second main surface of the first layer, wherein a first resistance between the second main surface of the first layer and the second main surface of the second layer and a second resistance between the first main surface of the first layer and the second main surface of the fourth layer change based on the magnetization direction of the first layer.
1 . A magnetic memory device comprising a stacked structure including:
a first layer including first and second main surfaces, and having a variable magnetization direction;
a second layer including first and second main surfaces, and having a fixed magnetization direction;
a third layer provided between the first layer and the second layer, adjacent to the first main surface of the first layer and the first main surface of the second layer, and functioning as a tunnel barrier; and
a conductive fourth layer including first and second main surfaces, the first main surface of the fourth layer being adjacent to the second main surface of the first layer, wherein
a first resistance between the second main surface of the first layer and the second main surface of the second layer and a second resistance between the first main surface of the first layer and the second main surface of the fourth layer change based on the magnetization direction of the first layer.
2 . The magnetic memory device of claim 1 , wherein
the first layer is selectively in a first state where the magnetization direction is parallel to the magnetization direction of the second layer, and in a second state where the magnetization direction is antiparallel to the magnetization direction of the second layer.
3 . The magnetic memory device of claim 2 , wherein
both the first resistance and the second resistance are low when the first layer is in the first state in comparison with when the first layer is in the second state.
4 . The magnetic memory device of claim 1 , wherein
the magnetization direction of the first layer is parallel to the main surfaces of the first layer, and
the magnetization direction of the second layer is parallel to the main surfaces of the second layer.
5 . The magnetic memory device of claim 1 , wherein
the magnetization direction of the first layer is perpendicular to the main surfaces of the first layer, and
the magnetization direction of the second layer is perpendicular to the main surfaces of the second layer.
6 . The magnetic memory device of claim 1 , wherein
the first resistance depends on resistance based on a tunnel magnetoresistive effect generated by the first layer, the second layer and the third layer.
7 . The magnetic memory device of claim 1 , wherein
the fourth layer has antiferromagnetism or ferrimagnetism.
8 . The magnetic memory device of claim 7 , wherein
a spin direction of the fourth layer changes based on the magnetization direction of the first layer.
9 . The magnetic memory device of claim 7 , wherein
the magnetization direction of the first layer is parallel to the main surfaces of the first layer,
the magnetization direction of the second layer is parallel to the main surfaces of the second layer, and
a spin direction of the fourth layer is parallel to the main surfaces of the fourth layer.
10 . The magnetic memory device of claim 7 , wherein
the magnetization direction of the first layer is perpendicular to the main surfaces of the first layer,
the magnetization direction of the second layer is perpendicular to the main surfaces of the second layer, and
a spin direction of the fourth layer is perpendicular to the main surfaces of the fourth layer.
11 . The magnetic memory device of claim 7 , wherein
the magnetization direction of the first layer is perpendicular to the main surfaces of the first layer,
the magnetization direction of the second layer is perpendicular to the main surfaces of the second layer, and
a spin direction of the fourth layer is parallel to the main surfaces of the fourth layer.
12 . The magnetic memory device of claim 7 , wherein
the second resistance depends on resistance based on a magnetoresistive effect applied between the first layer and the fourth layer.
13 . The magnetic memory device of claim 7 , wherein
the fourth layer is formed of an Mn-based alloy, an oxide of a ferromagnetic element, a rare-earth-metal-based alloy or a ferrimagnetic material.
14 . The magnetic memory device of claim 1 , wherein
the first layer contains iron (Fe) and cobalt (Co).
15 . The magnetic memory device of claim 14 , wherein
the first layer further contains boron (B).
16 . The magnetic memory device of claim 1 , wherein
the second layer includes a first sub-magnetic layer portion containing iron (Fe) and cobalt (Co).
17 . The magnetic memory device of claim 16 , wherein
the first sub-magnetic layer portion further contains boron (B).
18 . The magnetic memory device of claim 16 , wherein
the second layer further includes a second sub-magnetic layer portion containing at least one of cobalt (Co) and iron (Fe), and at least one element selected from platinum (Pt), nickel (Ni) and palladium (Pd).
19 . The magnetic memory device of claim 1 , wherein
the third layer is formed of an oxide insulating material.
20 . The magnetic memory device of claim 1 , wherein
the stacked structure further includes a fifth layer adjacent to the second main surface of the second layer and having a fixed magnetization direction antiparallel to the magnetization direction of the second layer.