Master medium for magnetic transfer, magnetic transferring and recording method, slave medium for magnetic recording, and method for producing a master medium for magnetic transfer
View Patent ↗A master medium for magnetic transfer includes a substrate having a concave portion formed in its surface corresponding to a pattern of recorded information to be transferred; a first perpendicular ferromagnetic layer deposited in the concave portion; and a second perpendicular ferromagnetic layer layered on the substrate surface and the first perpendicular ferromagnetic layer surface. The substrate surface and the first perpendicular ferromagnetic layer surface are flattened to form a single flat surface. In the master medium for magnetic transfer, a magnetic field change in a direction parallel to the substrate surface at a magnetization boundary of the first perpendicular ferromagnetic layer is steep. Since the influence of the change of an external magnetic field is reduced, it is possible to perform accurate transfer from the master medium for magnetic transfer to a slave medium for magnetic recording.
1. A master medium for magnetic transfer comprising:
a non-magnetic substrate;
a first perpendicular ferromagnetic layer deposited in a concave portion formed in a surface of the substrate; and
a second perpendicular ferromagnetic layer layered on the surface of the substrate and a surface of the first perpendicular ferromagnetic layer.
2. The master medium for magnetic transfer according to claim 1 ,
wherein the surface of the substrate and the surface of the first perpendicular ferromagnetic layer are flattened to form a single flat surface.
3. The master medium for magnetic transfer according to claim 2 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are parallel to each other.
4. The master medium for magnetic transfer according to claim 2 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are anti-parallel to each other, and
saturation magnetization Ms 1 and layer thickness t 1 of the first perpendicular ferromagnetic layer and saturation magnetization Ms 2 and layer thickness t 2 of the second perpendicular ferromagnetic layer satisfy a relation Ms 1 ·t 1 >Ms 2 ·t 2 .
5. The master medium for magnetic transfer according to claim 1 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are parallel to each other.
6. The master medium for magnetic transfer according to claim 1 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are anti-parallel to each other, and
saturation magnetization Ms 1 and layer thickness t 1 of the first perpendicular ferromagnetic layer and saturation magnetization Ms 2 and layer thickness t 2 of the second perpendicular ferromagnetic layer satisfy a relation Ms 1 ·t 1 >Ms 2 ·t 2 .
7. A magnetic transferring and recording method for transferring recorded information on a master medium for magnetic transfer to a slave medium for magnetic recording, comprising the steps of:
preparing the master medium for magnetic transfer which comprises a non-magnetic substrate, a first perpendicular ferromagnetic layer deposited in a concave portion formed in a surface of the substrate, and a second perpendicular ferromagnetic layer layered on the surface of the substrate and a surface of the first perpendicular ferromagnetic layer;
juxtaposing the master medium for magnetic transfer and the slave medium for magnetic recording having a perpendicular anisotropy whose magnetization has been initialized in one direction in advance; and
applying an external magnetic field of a direction opposite to the initialized magnetization direction of the slave medium for magnetic recording.
8. The magnetic transferring and recording method according to claim 7 ,
wherein the surface of the substrate and the surface of the first perpendicular ferromagnetic layer are flattened to form a single flat surface.
9. The magnetic transferring and recording method according to claim 8 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are parallel to each other.
10. The magnetic transferring and recording method according to claim 8 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are anti-parallel to each other, and
saturation magnetization Ms 1 and layer thickness t 1 of the first perpendicular ferromagnetic layer and saturation magnetization Ms 2 and layer thickness t 2 of the second perpendicular ferromagnetic layer satisfy a relation Ms 1 ·t 1 >Ms 2 ·t 2 .
11. The magnetic transferring and recording method according to claim 7 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are parallel to each other.
12. The magnetic transferring and recording method according to claim 7 ,
wherein exchange coupling is performed so that a magnetization direction of the first perpendicular ferromagnetic layer and a magnetization direction of the second perpendicular ferromagnetic layer are anti-parallel to each other, and
saturation magnetization Ms 1 and layer thickness t 1 of the first perpendicular ferromagnetic layer and saturation magnetization Ms 2 and layer thickness t 2 of the second perpendicular ferromagnetic layer satisfy a relation Ms 1 ·t 1 >Ms 2 ·t 2 .
13. A method for producing a master medium for magnetic transfer having a first perpendicular ferromagnetic layer and a second perpendicular ferromagnetic layer on a substrate surface, comprising:
the step of forming a concave portion in the substrate surface;
the step of forming the first perpendicular ferromagnetic layer in the concave portion by depositing the first perpendicular ferromagnetic layer on the substrate surface;
a flattening step of flattening the substrate surface and a surface of the first perpendicular ferromagnetic layer to form a single flat surface; and
a depositing step of depositing the second perpendicular ferromagnetic layer on the flattened substrate surface and first perpendicular ferromagnetic layer surface.
14. The method for producing a master medium for magnetic transfer according to claim 13 , further comprising the step of etching the flattened substrate surface and first perpendicular ferromagnetic layer surface, between the flattening step and depositing step.