Magnetic multilayer film, magnetic memory element, magnetic memory and method for producing same
The magnetic memory element ( 100 ) includes: a conductive layer that includes a heavy metal layer ( 10 ) containing a 5d transition metal; a first ferromagnetic layer ( 20 ) that is adjacent to the conductive layer and contains a ferromagnetic layer having a reversible magnetization; a barrier layer ( 30 ) that is adjacent to the first ferromagnetic layer ( 20 ) and includes an insulating material; a reference layer ( 40 ) that is adjacent to the barrier layer ( 30 ) and has at least one second ferromagnetic layer ( 41 ) having a fixed magnetization direction; a cap layer ( 50 ) that is adjacent to the reference layer ( 40 ) and includes a conductive material; a first terminal (T 1 ) that is capable of introducing a current into one end of the heavy metal layer ( 10 ) in the longitudinal direction; a second terminal (T 2 ) that is capable of introducing a current into the other end of the heavy metal layer ( 10 ) in the longitudinal direction; and a third terminal (T 3 ) that is capable of introducing a current into the cap layer ( 50 ).
1. A magnetic multilayer film for a magnetic memory element, the magnetic multilayer film comprising:
a conductive layer that includes a heavy metal layer containing a 5d transition metal; and
a first ferromagnetic layer that is adjacent to the conductive layer and contains a ferromagnetic layer having a reversible magnetization,
wherein
a film thickness of the conductive layer is 6 nm or more, and
a crystal structure of the heavy metal layer is amorphous or β-phase.
2. A magnetic multilayer film for a magnetic memory element, the magnetic multilayer film comprising:
a conductive layer that includes a heavy metal layer containing a 5d transition metal; and
a first ferromagnetic layer that is adjacent to the conductive layer and contains a ferromagnetic layer having a reversible magnetization,
wherein
a film thickness of the conductive layer is 6 nm or more, and
a resistivity of the heavy metal layer is 100 μΩ cm or more.
3. The magnetic multilayer film according to claim 2 , wherein a crystal structure of the heavy metal layer is amorphous or β-phase.
4. The magnetic multilayer film according to claim 1 , wherein the conductive layer further includes an adjustment layer that is adjacent to the heavy metal layer and that includes a conductive material.
5. The magnetic multilayer film according to claim 1 , wherein the heavy metal layer contains Ta or W.
6. A magnetic memory element, comprising:
the magnetic multilayer film according to claim 1 ;
a barrier layer that is adjacent to the first ferromagnetic layer and includes an insulating material;
a reference layer that is adjacent to the barrier layer and includes at least one ferromagnetic layer having a fixed magnetization direction;
a cap layer that is adjacent to the reference layer and includes a conductive material;
a first terminal that is capable of introducing a current into one end of the heavy metal layer in the longitudinal direction;
a second terminal that is capable of introducing a current into the other end of the heavy metal layer in the longitudinal direction; and
a third terminal that is capable of introducing a current into the cap layer.
7. The magnetic memory element according to claim 6 , comprising a fourth terminal connected to the first ferromagnetic layer.
8. The magnetic memory element according to claim 6 , wherein the first ferromagnetic layer has a reversible magnetization in a direction perpendicular to a film surface of the first ferromagnetic layer.
9. The magnetic memory element according to claim 6 , wherein the first ferromagnetic layer has a reversible magnetization in a direction orthogonal to a line segment connecting the first terminal and the second terminal within a film surface of the first ferromagnetic layer.
10. The magnetic memory element according to claim 6 , wherein the first ferromagnetic layer has a reversible magnetization in a direction parallel to a line segment connecting the first terminal and the second terminal within a film surface of the first ferromagnetic layer.
11. The magnetic memory element according to claim 6 , wherein
the first ferromagnetic layer includes a first magnetized area, and a second magnetized area and a third magnetized area arranged across the first magnetized area,
a magnetization of the second magnetized area and a magnetization of the third magnetized area are fixed in mutually different directions, and
a magnetization of the first magnetized area is reversible and can be oriented in the same direction as any one of a magnetization of the second magnetized area and a magnetization of the third magnetized area.
12. A magnetic memory, comprising:
the magnetic memory element according to any of claim 6 ;
write means for writing data to the magnetic memory element by feeding a write current to the magnetic memory element; and
read means for reading data written into the magnetic memory element by determining a tunnel resistance by feeding a current in a direction penetrating the barrier layer.
13. The magnetic multilayer film according to claim 1 , wherein
the heavy metal layer is deposited by magnetron sputtering,
a partial pressure of an inert gas in a film forming process is 0.1 Pa or more,
a mean free path of a sputtered particle in a film forming process is shorter than a distance between a target of sputtering and a substrate of the sputtering,
a deposition rate of a thin film in a film forming process is 0.02 nm/s or less,
a substrate temperature is set to a room temperature or less in a film forming process, and
a bias voltage is applied to a substrate in a film forming process.
14. A method for producing a magnetic multilayer film or a magnetic memory element including the magnetic multilayer film, the magnetic multilayer film including:
a heavy metal layer containing a 5d transition metal; and
a first ferromagnetic layer that is adjacent to the heavy metal layer and contains a ferromagnetic layer having a reversible magnetization,
wherein
the heavy metal layer is deposited by magnetron sputtering, and
a partial pressure of an inert gas in a film forming process is 0.1 Pa or more.
15. A method for producing a magnetic multilayer film or a magnetic memory element including the magnetic multilayer film, the magnetic multilayer film including:
a heavy metal layer containing a 5d transition metal; and
a first ferromagnetic layer that is adjacent to the heavy metal layer and contains a ferromagnetic layer having a reversible magnetization,
wherein
the heavy metal layer is deposited by magnetron sputtering, and
a mean free path of a sputtered particle in a film forming process is shorter than a distance between a target of sputtering and a substrate of the sputtering.
16. The method for producing a magnetic multilayer film or a magnetic memory element according to claim 14 , wherein a deposition rate of a thin film in a film forming process of the heavy metal layer is 0.02 nm/s or less.
17. The method for producing a magnetic multilayer film or a magnetic memory element according to claim 14 , wherein a substrate temperature is set to a room temperature or less in a film forming process of the heavy metal layer.
18. The method for producing a magnetic multilayer film or a magnetic memory element according to claim 14 , wherein a bias voltage is applied to a substrate in a film forming process of the heavy metal layer.