Magnetic recording head and magnetic recording and reproducing device
According to one embodiment, a magnetic recording head includes a magnetic pole, a stacked body, and a first nonmagnetic layer. The stacked body includes first magnetic layer, a second magnetic layer provided between the first magnetic layer and the magnetic pole, and an intermediate layer provided between the first magnetic layer and the second magnetic layer and being nonmagnetic. The first nonmagnetic layer is provided between the second magnetic layer and the magnetic pole. A product of a thickness and a saturation magnetic flux density of the second magnetic layer is larger than a product of a thickness and a saturation magnetic flux density of the first magnetic layer. The length of the first magnetic layer is shorter than a length of the second magnetic layer. A current flows from the second magnetic layer toward the first magnetic layer.
1. A magnetic recording head, comprising:
a magnetic pole;
a stacked body including
a first magnetic layer,
a second magnetic layer provided between the first magnetic layer and the magnetic pole, and
an intermediate layer provided between the first magnetic layer and the second magnetic layer and being nonmagnetic; and
a first nonmagnetic layer provided between the second magnetic layer and the magnetic pole and contacting the magnetic pole and the second magnetic layer,
the first magnetic layer having a first thickness and a first saturation magnetic flux density, the first thickness being along a first direction, the first direction being from the second magnetic layer toward the first magnetic layer,
the second magnetic layer having a second thickness and a second saturation magnetic flux density, the second thickness being along the first direction,
a second product of the second thickness and the second saturation magnetic flux density being larger than a first product of the first thickness and the first saturation magnetic flux density,
a first length of the first magnetic layer in a second direction being shorter than a second length of the second magnetic layer in the second direction, the second direction being perpendicular to the first direction,
a current flowing from the second magnetic layer toward the first magnetic layer.
2. The head according to claim 1 , wherein
the magnetic pole has a medium-opposing surface, and
the second direction crosses the medium-opposing surface.
3. The head according to claim 1 , wherein
the magnetic pole has a medium-opposing surface, and
the second direction is aligned with the medium-opposing surface.
4. The head according to claim 1 , wherein a length of the first magnetic layer in a third direction is shorter than a length of the second magnetic layer in the third direction, the third direction crossing the second direction and being perpendicular to the first direction.
5. The head according to claim 1 , wherein
the first magnetic layer has a first side surface crossing the second direction,
the second magnetic layer has a second side surface crossing the second direction, and
the second side surface is in a plane including the first side surface.
6. The head according to claim 1 , wherein
the first magnetic layer has a first side surface crossing the second direction, and
the first side surface is tilted with respect to the first direction.
7. The head according to claim 1 , wherein
the second magnetic layer has a second side surface crossing the second direction, and
the second side surface is tilted with respect to the first direction.
8. The head according to claim 1 , wherein the second length is 1.05 times the first length or more.
9. The head according to claim 1 , wherein the intermediate layer includes an oxide.
10. The head according to claim 1 , wherein
in a first state, a first magnetic-pole magnetic field is generated from the magnetic pole and has a component along the first direction,
in a second state, a second magnetic-pole magnetic field is generated from the magnetic pole and has a component along a first reverse direction, the first reverse direction being from the first magnetic layer toward the second magnetic layer, and
in the first state, a magnetization of the first magnetic layer has a component in the first reverse direction.
11. The head according to claim 10 , wherein a magnetization of the first magnetic layer has a component in the first direction in the second state.
12. The head according to claim 10 , wherein the stacked body generates a magnetic wave.
13. The head according to claim 12 , wherein a frequency of the magnetic wave is not less than 5 gigahertz and not more than 25 gigahertz.
14. The head according to claim 10 , further comprising a coil,
in the first state, the first magnetic-pole magnetic field being generated from the magnetic pole by supplying a first coil current to the coil,
in the second state, the second magnetic-pole magnetic field being generated from the magnetic pole by supplying a second coil current to the coil.
15. The head according to claim 14 , further comprising a controller,
the controller supplying the current to the stacked body,
in a first operation, the controller supplying the first coil current to the coil while supplying the current to the stacked body,
in a second operation, the controller supplying a second coil current to the coil while supplying the current to the stacked body, the second coil current having the reverse orientation of the first coil current.
16. A magnetic recording head, comprising:
a magnetic pole;
a shield;
a stacked body including
a first magnetic layer provided between the magnetic pole and the shield,
a second magnetic layer provided between the first magnetic layer and the shield, and
an intermediate layer provided between the first magnetic layer and the second magnetic layer and being nonmagnetic; and
a first nonmagnetic layer provided between the second magnetic layer and the shield and contacting the shield and the second magnetic layer,
the first magnetic layer having a first thickness and a first saturation magnetic flux density, the first thickness being along a first direction, the first direction being from the second magnetic layer toward the first magnetic layer,
the second magnetic layer having a second thickness and a second saturation magnetic flux density, the second thickness being along the first direction,
a second product of the second thickness and the second saturation magnetic flux density being larger than a first product of the first thickness and the first saturation magnetic flux density,
a first length of the first magnetic layer in a second direction being shorter than a second length of the second magnetic layer in the second direction, the second direction being perpendicular to the first direction,
a current flowing from the second magnetic layer toward the first magnetic layer.
17. The magnetic recording head according to claim 16 , wherein the shield is a trailing shield.
18. A magnetic recording and reproducing device, comprising:
a magnetic recording head, including:
a magnetic pole;
a stacked body including
a first magnetic layer,
a second magnetic layer provided between the first magnetic layer and the magnetic pole, and
an intermediate layer provided between the first magnetic layer and the second magnetic layer and being nonmagnetic; and
a first nonmagnetic layer provided between the second magnetic layer and the magnetic pole and contacting the magnetic pole and the second magnetic layer,
the first magnetic layer having a first thickness and a first saturation magnetic flux density, the first thickness being along a first direction, the first direction being from the second magnetic layer toward the first magnetic layer,
the second magnetic layer having a second thickness and a second saturation magnetic flux density, the second thickness being along the first direction,
a second product of the second thickness and the second saturation magnetic flux density being larger than a first product of the first thickness and the first saturation magnetic flux density,
a first length of the first magnetic layer in a second direction being shorter than a second length of the second magnetic layer in the second direction, the second direction being perpendicular to the first direction,
a current flowing from the second magnetic layer toward the first magnetic layer;
a magnetic recording medium, information being recorded on the magnetic recording medium by the magnetic head; and
a controller configured to flow the current in the stacked body.
19. The device according to claim 18 , wherein
the magnetic recording head further includes a coil,
in a first operation, the controller causes the magnetic pole to generate a first magnetic-pole magnetic field having a component along the first direction by supplying a first coil current to the coil, and
in a second operation, the controller causes the magnetic pole to generate a second magnetic-pole magnetic field having a component along a first reverse direction by supplying a second coil current to the coil, the first reverse direction being from the first magnetic layer toward the second magnetic layer.
20. The device according to claim 18 , wherein the magnetic recording medium is a perpendicular magnetic recording media.