MAGNETIC MEMORY DEVICE
According to one embodiment, a magnetic memory device includes a stacked structure which comprises a first magnetic layer having a variable magnetization direction, a second magnetic layer, and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer, and is allowed to be selectively set to a low-resistance state and a high-resistance state having a resistance greater than that of the low-resistance state based on a magnetization direction of the first magnetic layer, the high-resistance state being stable in a stationary state where no current flows through the stacked structure, and a magnetic field supply unit which supplies, to the first magnetic layer, a magnetic field having a direction opposite to a direction of a vertical magnetic field component of a total magnetic field applied from the second magnetic layer to the first magnetic layer.
1 . A magnetic memory device comprising:
a stacked structure which comprises a first magnetic layer having a variable magnetization direction, a second magnetic layer, and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer, and is allowed to be selectively set to a low-resistance state and a high-resistance state having a resistance greater than that of the low-resistance state based on a magnetization direction of the first magnetic layer, the high-resistance state being stable in a stationary state where no current flows through the stacked structure; and
a magnetic field supply unit which supplies, to the first magnetic layer, a magnetic field having a direction opposite to a direction of a vertical magnetic field component of a total magnetic field applied from the second magnetic layer to the first magnetic layer.
2 . The magnetic memory device of claim 1 , wherein
a direction of a read current flowing through the stacked structure is the same as that of a write current flowing through the stacked structure for setting the stacked structure to the low-resistance state.
3 . The magnetic memory device of claim 1 , wherein
the second magnetic layer includes a first sub-magnetic layer having a fixed first magnetization direction, and a second sub-magnetic layer having a fixed second magnetization direction antiparallel to the first magnetization direction, and the first sub-magnetic layer is provided between the nonmagnetic layer and the second sub-magnetic layer, and
a magnetic field applied from the second sub-magnetic layer to the first magnetic layer is greater than a magnetic field applied from the first sub-magnetic layer to the first magnetic layer.
4 . The magnetic memory device of claim 3 , wherein
the stacked structure is set to the low-resistance state when the magnetization direction of the first magnetic layer is parallel to the magnetization direction of the first sub-magnetic layer, and
the stacked structure is set to the high-resistance state when the magnetization direction of the first magnetic layer is antiparallel to the magnetization direction of the first sub-magnetic layer.
5 . The magnetic memory device of claim 3 , wherein
the first sub-magnetic layer contains iron (Fe) and boron (B).
6 . The magnetic memory device of claim 5 , wherein
the first sub-magnetic layer further contains cobalt (Co).
7 . The magnetic memory device of claim 3 , wherein
the magnetic field applied from the second sub-magnetic layer to the first magnetic layer is decreased as a temperature of the second sub-magnetic layer is increased.
8 . The magnetic memory device of claim 7 , wherein
the temperature of the second sub-magnetic layer is increased by supplying a write current to the stacked structure.
9 . The magnetic memory device of claim 7 , wherein
the second sub-magnetic layer includes a first material layer containing iron (Fe) and at least one element selected from terbium (Tb), gadolinium (Gd), dysprosium (Dy), rhodium (Rh) and manganese (Mn).
10 . The magnetic memory device of claim 9 , wherein
the second sub-magnetic layer further includes a second material layer containing cobalt (Co) and at least one element selected from platinum (Pt), nickel (Ni), palladium (Pd) and rhodium (Rh).
11 . The magnetic memory device of claim 7 , wherein
the second sub-magnetic layer includes at least one material layer selected from a first material layer, a second material layer and a third material layer,
the first material layer has an amorphous structure and contains iron (Fe) and at least one of boron (B) and phosphorus (P),
the second material layer has an amorphous structure and contains iron (Fe) and at least one rare-earth element, and
the third material layer has a bcc-crystal structure and contains iron (Fe).
12 . The magnetic memory device of claim 3 , further comprising
an interconnection electrically connected to the stacked structure, wherein
the interconnection includes a first portion, a second portion and a third portion arranged in an extension direction of the interconnection,
the second portion is provided at a position corresponding to a position of a pattern of the stacked structure, and has a magnetization direction parallel to the extension direction of the interconnection in a stationary state where no current flows through the interconnection,
the first portion is adjacent to one end of the second portion, and has a magnetization direction parallel to the magnetization direction of the second sub-magnetic layer, and
the third portion is adjacent to the other end of the second portion, and has a magnetization direction antiparallel to the magnetization direction of the second sub-magnetic layer.
13 . The magnetic memory device of claim 12 , wherein
all of a width of the interconnection, a length of the first portion, a length of the second portion and a length of the third portion are greater than a thickness of the second portion, and less than a thickness of the first portion and a thickness of the third portion.
14 . The magnetic memory device of claim 12 , wherein
a magnetization direction of the second portion is set to a magnetization direction antiparallel to the magnetization direction of the second sub-magnetic layer when a write current for the stacked structure is supplied to the interconnection.
15 . The magnetic memory device of claim 12 , wherein
a magnetization direction of the second portion is set to a magnetization direction parallel to the extension direction of the interconnection or a magnetization direction parallel to the magnetization direction of the second sub-magnetic layer when a read current for the stacked structure is supplied to the interconnection.
16 . The magnetic memory device of claim 12 , wherein
a material of the interconnection is selected from a magnetic material containing iron (Fe) and nickel (Ni), a magnetic material containing iron (Fe), silicon (Si) and aluminum (Al), a magnetic material containing iron (Fe) and oxygen (O), and an amorphous magnetic material.
17 . The magnetic memory device of claim 1 , wherein
the first magnetic layer contains iron (Fe) and boron (B).
18 . The magnetic memory device of claim 17 , wherein
the first magnetic layer further contains cobalt (Co).
19 . The magnetic memory device of claim 1 , wherein
the nonmagnetic layer contains magnesium (Mg) and oxygen (C).
20 . The magnetic memory device of claim 1 , wherein
the magnetic field supply unit is provided away from the stacked structure.