High-frequency magnetic field generation element and magnetic head
According to one embodiment, a high-frequency magnetic field generation element includes a first fixed layer, a first free layer, and a second free layer. A direction of a magnetization of the first fixed layer is fixed and has a component parallel to a first direction. A direction of a magnetization of the first free layer is variable and has a component orthogonal to the first direction. A direction of a magnetization of the second free layer is variable and has a component orthogonal to the first direction. The first fixed layer is provided between the first free layer and the second free layer. The magnetizations of the first free layer and the second free layer oscillate. A rotation direction of the magnetization of the first free layer is opposite to a rotation direction of the magnetization of the second free layer.
1. A high-frequency magnetic field generation element comprising:
a first fixed layer, a direction of a magnetization of the first fixed layer being fixed and including a component parallel to a first direction;
a first free layer stacked with the first fixed layer, a direction of a magnetization of the first free layer being variable and including a component orthogonal to the first direction; and
a second free layer stacked with the first fixed layer, a direction of a magnetization of the second free layer being variable and including a component orthogonal to the first direction,
the first fixed layer being provided between the first free layer and the second free layer,
the first direction being parallel to a stacking direction of the first fixed layer, the first free layer, and the second free layer,
the magnetization of the first free layer and the magnetization of the second free layer oscillating by a current flowing through the first free layer, the second free layer, and the first fixed layer, and
a rotation direction of the magnetization in the oscillation of the first free layer being opposite to a rotation direction of the magnetization in the oscillation of the second free layer.
2. The element according to claim 1 , wherein the magnetization of the first free layer and the magnetization of the second free layer oscillate in synchronization with a high-frequency signal superposed on the current.
3. The element according to claim 1 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization by at least one of interaction by the current, interaction via a spin current, and dipole interaction.
4. The element according to claim 1 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization with a frequency of a high-frequency magnetic field applied from an outside.
5. The element according to claim 1 , wherein the direction of the magnetization of the first free layer and the direction of the magnetization of the second free layer are identical to each other when the direction of the magnetization of the first free layer rotated by the oscillation and the direction of the magnetization of the second free layer rotated by the oscillation are parallel to a recording surface of a magnetic recording medium and the direction of the magnetization of the first free layer and the direction of the magnetization of the second free layer are opposite to each other when the direction of the magnetization of the first free layer rotated by the oscillation and the direction of the magnetization of the second free layer rotated by the oscillation are perpendicular to the recording surface.
6. A high-frequency magnetic field generation element comprising:
a first fixed layer, a direction of a magnetization of the first fixed layer being fixed and including a component parallel to a first direction;
a first free layer stacked with the first fixed layer, a direction of a magnetization of the first free layer being variable and including a component orthogonal to the first direction;
a second fixed layer, a direction of a magnetization of the second fixed layer being fixed and including a component parallel to the first direction; and
a second free layer stacked with the second fixed layer, a direction of a magnetization of the second free layer being variable and including a component orthogonal to the first direction,
the first direction being parallel to a stacking direction of the first fixed layer, the first free layer, and the second free layer,
the magnetization of the first free layer oscillating by a current flowing through the first fixed layer and the first free layer,
the magnetization of the second free layer oscillating by a current flowing through the second fixed layer and the second free layer, and
a rotation direction of the magnetization in the oscillation of the first free layer being opposite to a rotation direction of the magnetization in the oscillation of the second free layer.
7. The element according to claim 6 , wherein the magnetization of the first free layer and the magnetization of the second free layer oscillate in synchronization with a high-frequency signal superposed on the current flowing through the first free layer and the current flowing through the second free layer, respectively.
8. The element according to claim 6 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization by at least one of interaction by the current flowing through the first free layer and the current flowing through the second free layer, interaction via a spin current, and dipole interaction.
9. The element according to claim 6 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization with a frequency of a high-frequency magnetic field applied from an outside.
10. The element according to claim 6 , wherein the direction of the magnetization of the first free layer and the direction of the magnetization of the second free layer are identical to each other when the direction of the magnetization of the first free layer rotated by the oscillation and the direction of the magnetization of the second free layer rotated by the oscillation are parallel to a recording surface of a magnetic recording medium and the direction of the magnetization of the first free layer and the direction of the magnetization of the second free layer are opposite to each other when the direction of the magnetization of the first free layer rotated by the oscillation and the direction of the magnetization of the second free layer rotated by the oscillation are perpendicular to the recording surface.
11. The element according to claim 6 , further comprising:
a conductive unit provided between the first free layer and the second free layer,
the first free layer being provided between the conductive unit and the first fixed layer,
the second free layer being provided between the conductive unit and the second fixed layer.
12. The element according to claim 6 , further comprising:
a conductive unit provided between the first fixed layer and the second fixed layer,
the first fixed layer being provided between the conductive unit and the first free layer,
the second fixed layer being provided between the conductive unit and the second free layer.
13. A magnetic head comprising:
a main magnetic pole;
a coil for recording configured to generate a recording magnetic field in the main magnetic pole; and
a high-frequency magnetic field generation element disposed along with the main magnetic pole,
the high-frequency magnetic field generation element including:
a first fixed layer, a direction of a magnetization of the first fixed layer being fixed and including a component parallel to a first direction;
a first free layer stacked with the first fixed layer, a direction of a magnetization of the first free layer being variable and including a component orthogonal to the first direction; and
a second free layer stacked with the first fixed layer, a direction of a magnetization of the second free layer being variable and including a component orthogonal to the first direction,
the first fixed layer being provided between the first free layer and the second free layer,
the first direction being parallel to a stacking direction of the first fixed layer, the first free layer, and the second free layer,
the magnetization of the first free layer and the magnetization of the second free layer oscillating by a current flowing through the first free layer, the second free layer, and the first fixed layer, and
a rotation direction of the magnetization in the oscillation of the first free layer being opposite to a rotation direction of the magnetization in the oscillation of the second free layer.
14. The magnetic head according to claim 13 , further comprising:
a return path opposed to the main magnetic pole,
at least part of the high-frequency magnetic field generation element being disposed between the main magnetic pole and the return path.
15. The magnetic head according to claim 13 , wherein
the high-frequency magnetic field generation element further includes:
a conductive unit provided between the first free layer and the second free layer, and
a second fixed layer, a direction of a magnetization of the second fixed layer being fixed and including a component parallel to the first direction,
the first free layer is provided between the conductive unit and the first fixed layer,
the second free layer is provided between the conductive unit and the second fixed layer, and
the main magnetic pole is electrically connected to the conductive unit.
16. The magnetic head according to claim 13 , wherein
the high-frequency magnetic field generation element further includes:
a second fixed layer, a direction of a magnetization of the second fixed layer being fixed and including a component parallel to the first direction, and
a conductive unit provided between the first fixed layer and the second fixed layer,
the first fixed layer is provided between the conductive unit and the first free layer,
the second fixed layer is provided between the conductive unit and the second free layer, and
the main magnetic pole is electrically connected to the conductive unit.
17. The magnetic head according to claim 13 , further comprising a detection unit configured to detect a high-frequency component from a current flowing through the high-frequency magnetic field generation element.
18. The magnetic head according to claim 13 , wherein the magnetization of the first free layer and the magnetization of the second free layer oscillate in synchronization with a high-frequency signal superposed on the current.
19. The magnetic head according to claim 13 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization by at least one of interaction by the current, interaction via a spin current, and dipole interaction.
20. The magnetic head according to claim 13 , wherein the magnetization of the first free layer and the magnetization of the second free layer rotate in synchronization with a frequency of a high-frequency magnetic field applied from an outside.