Memory device
According to one embodiment, a memory device includes a stacked structure and a controller. The stacked structure includes a first magnetic layer, a second magnetic layer stacked with the first magnetic layer, and a first nonmagnetic layer provided between the first magnetic layer and the second magnetic layer. The second magnetic layer includes a first portion and a second portion stacked with the first portion. A magnetic resonance frequency of the first portion is different from a magnetic resonance frequency of the second portion. The controller is electrically connected to the stacked structure and causes a pulse current to flow in the stacked body in a first period. A length of the first period is not less than 0.9 times and not more than 1.1 times the absolute value of an odd number times of the reciprocal of a magnetic resonance frequency of the second magnetic layer.
1. A memory device comprising:
a stacked structure including
a first magnetic layer,
a second magnetic layer stacked with the first magnetic layer, the second magnetic layer including
a first portion, and
a second portion stacked with the first portion in a stacking direction of the first magnetic layer and the second magnetic layer, a magnetic resonance frequency of the first portion being different from a magnetic resonance frequency of the second portion, and
a first nonmagnetic layer provided between the first magnetic layer and the second magnetic layer; and
a controller electrically connected to the stacked structure, the controller causing
a pulse current having a magnitude of a first value to flow in the stacked structure in a first period,
no current to flow in the stacked structure in a second period before the first period, and
no current to flow in the stacked structure in a third period after the first period, wherein
a length of the first period being not less than 0.9 times and not more than 1.1 times the absolute value of an odd number times of the reciprocal of a magnetic resonance frequency of the second magnetic layer.
2. The device according to claim 1 , wherein
the magnetic resonance frequency of the first portion is a first magnetic resonance frequency, and
the magnetic resonance frequency of the second portion is a second magnetic resonance frequency lower than the first magnetic resonance frequency.
3. The device according to claim 2 , wherein at least one selected from a group consisting of the first portion and the second portion includes a Heusler alloy including at least one selected from a group consisting of Co, Mn, Fe, Ni, Cu, Rh, Ru, and Pd.
4. The device according to claim 2 , wherein at least one selected from a group consisting of the first portion and the second portion includes at least one selected from a group consisting of Co 2 FeSi, Co 2 FeAl, Co 2 FeGa, Co 2 MnGe, Co 2 MnSn, Co 2 MnSi, Co 2 MnGa, Co 2 MnAl, Co 2 MnSb, Co 2 CrGa, Ni 2 MnIn, Ni 2 MnGa, Ni 2 MnSn, Ni 2 MnSb, Ni 2 ,FeGa, Pd 2 MnSb, Pd 2 MnSn, Cu 2 MnAl, Cu 2 MnSn, Cu 2 MnIn, Rh 2 MnGe, Rh 2 MnPb, Rh 2 MnSn, Pd 2 MnGe, Rh 2 FeSn, Ru 2 FeSn, and Rh 2 FeSb.
5. The device according to claim 2 , wherein at least one selected from a group consisting of the first portion and the second portion includes at least one selected from a group consisting of Co 2 HfSn, Co 2 ZrSn, Co 2 HfAl, Co 2 ZrAl, CO 2 HfGa, Co 2 TiSi, Co 2 TiGe, Co 2 TiSn, Co 2 TiGa, Co 2 TiAl, Co 2 VGa, Co 2 VAl, Co 2 TaAl, Co 2 NbGa, Co 2 NbAl, Co 2 VSn, Co 2 NbSn, Co 2 CrAl, Rh 2 NiSn, Rh 2 NiGe, Mn 2 WSn, Fe 2 MnSi, and Fe 2 MnAl.
6. The device according to claim 2 , wherein
the first portion includes at least one selected from a group consisting of Co 2 HfSn, Co 2 ZrSn, Co 2 HfAl, Co 2 ZrAl, Co 2 HfGa, Co 2 TiSi, Co 2 TiGe, Co 2 TiSn, Co 2 TiGa, Co 2 TiAl, Co 2 VGa, Co 2 VAl, Co 2 TaAl, Co 2 NbGa, Co 2 NbAl, Co 2 VSn, Co 2 NbSn, Co 2 CrAl, Rh 2 NiSn, Rh 2 NiGe, Mn 2 WSn, Fe 2 MnSi, and Fe 2 MnAl, and
the second portion includes at least one selected from a group consisting of Co 2 FeSi, Co 2 FeAl, Co 2 FeGa, Co 2 MnGe, Co 2 MnSn, Co 2 MnSi, Co 2 MnGa, Co 2 MnAl, Co 2 MnSb, Co 2 CrGa, Ni 2 MnIn, Ni 2 MnGa, Ni 2 MnSn, Ni 2 MnSb, Ni 2 FeGa, Pd 2 MnSb, Pd 2 MnSn, Cu 2 MnAl Cu 2 MnSn, Cu 2 MnIn, Rh 2 MnGe, Rh 2 MnPb, Rh 2 MnSn, Pd 2 MnGe, Rh 2 FeSn, Ru 2 FeSn, and Rh 2 FeSb.
7. The device according to claim 2 , wherein
the first magnetic resonance frequency is 20 GHz or more, and
the second magnetic resonance frequency is less than 20 GHz.
8. The device according to claim 1 , wherein
a perpendicular magnetization component parallel to the stacking direction of a magnetization of the first magnetic layer is larger than an in-plane magnetization component perpendicular to the stacking direction of the magnetization of the first magnetic layer,
the perpendicular magnetization component of a magnetization of the first portion is larger than the in-plane magnetization component of the magnetization of the first portion, and
the perpendicular magnetization component of a magnetization of the second portion is larger than the in-plane magnetization component of the magnetization of the second portion.
9. The device according to claim 1 , wherein
a plurality of the second magnetic layers and a plurality of the first nonmagnetic layers are provided,
the plurality of second magnetic layers is arranged in an in-plane direction perpendicular to the stacking direction, and
the plurality of first nonmagnetic layers is disposed respectively between the first magnetic layer and each of the plurality of second magnetic layers.
10. The device according to claim 1 , wherein
a plurality of the second magnetic layers is provided,
the plurality of second magnetic layers is arranged in an in-plane direction perpendicular to the stacking direction, and
the first nonmagnetic layer is disposed between the first magnetic layer and the plurality of second magnetic layers.
11. The device according to claim 1 , further comprising:
a first interconnect electrically connected to the first magnetic layer; and
a second interconnect electrically connected to the second magnetic layer,
the controller being connected to the stacked structure via the first interconnect and the second interconnect.
12. The device according to claim 11 , further comprising a selection transistor provided between the first magnetic layer and the first interconnect and/or between the second magnetic layer and the second interconnect.
13. The device according to claim 1 , wherein a length of the second magnetic layer in a direction perpendicular to the stacking direction is 35 nanometers or less.
14. The device according to claim 1 , further comprising a magnetic shield opposing at least a portion of a side surface of the stacked structure extending in the stacking direction.
15. The device according to claim 1 , wherein a length of the stacked structure in a direction perpendicular to the stacking direction decreases in a direction from the first magnetic layer toward the second magnetic layer.
16. The device according to claim 1 , wherein pulse width of the pulse current is 2 nanoseconds or less.
17. A memory device comprising:
a stacked structure including
a first magnetic layer,
a second magnetic layer stacked with the first magnetic layer, the second magnetic layer including
a first portion, and
a second portion stacked with the first portion in a stacking direction of the first magnetic layer and the second magnetic layer, a magnetic resonance frequency of the first portion being a first magnetic resonance frequency, a magnetic resonance frequency of the second portion being a second magnetic resonance frequency lower than the first magnetic resonance frequency, and
a first nonmagnetic layer provided between the first magnetic layer and the second magnetic layer; and
a controller electrically connected to the stacked structure and causing a pulse current having a magnitude of a first value to flow in the stacked structure in a first period, wherein
a length of the first period being not less than 0.9 times and not more than 1.1 times the absolute value of an odd number times of the reciprocal of a magnetic resonance frequency of the second magnetic layer, and
the magnetic resonance frequency of the second magnetic layer is between the first magnetic resonance frequency and the second magnetic resonance frequency.
18. A memory device comprising:
a stacked structure including
a first magnetic layer,
a second magnetic layer stacked with the first magnetic layer, the second magnetic layer including
a first portion, and
a second portion stacked with the first portion in a stacking direction of the first magnetic layer and the second magnetic layer, a magnetic resonance frequency of the first portion being different from a magnetic resonance frequency of the second portion, and
a first nonmagnetic layer provided between the first magnetic layer and the second magnetic layer; and
a controller electrically connected to the stacked structure and causing a pulse current having a magnitude of a first value to flow in the stacked structure in a first period, wherein
a length of the first period being not less than 0.9 times and not more than 1.1 times the absolute value of an odd number times of the reciprocal of a magnetic resonance frequency of the second magnetic layer, and
rise time of the pulse current being less than 300 picoseconds.