Magnetic recording medium and information storage apparatus
View Patent ↗A magnetic recording medium includes a nonmagnetic granular layer that has a granular structure in which a plurality of nonmagnetic grains made of a nonmagnetic material are separated from one another by a Cr oxide. The magnetic recording medium further includes a magnetic granular layer that is formed on the nonmagnetic granular layer and has a granular structure in which a plurality of magnetic grains made of a magnetic material are separated from one another by a nonmagnetic material.
1. A magnetic recording medium, comprising:
a nonmagnetic granular layer that has a granular structure in which a plurality of nonmagnetic grains made of a nonmagnetic material are separated from one another by a Cr oxide;
a magnetic granular layer that is formed on the nonmagnetic granular layer and has a granular structure in which a plurality of magnetic grains made of a magnetic material are separated from one another by a nonmagnetic material,
an interlayer made of a nonmagnetic material;
a soft magnetic underlayer made of a soft magnetic material; and
an underlayer that is formed on the soft magnetic underlayer, and is made of a nonmagnetic material having a face-centered cubic lattice crystal structure, and having a surface on which a [1,1,1] plane appears,
wherein the nonmagnetic granular layer is formed on the interlayer, and
wherein the interlayer is formed on the underlayer.
2. The magnetic recording medium according to claim 1 , wherein the magnetic granular layer is formed by growing the magnetic grains on the nonmagnetic grains in the nonmagnetic granular layer.
3. The magnetic recording medium according to claim 1 , wherein the nonmagnetic granular layer has, as the nonmagnetic grains, nonmagnetic grains of a hexagonal close-packed crystal structure whose C-axis orients in the thickness direction of the nonmagnetic granular layer.
4. The magnetic recording medium according to claim 1 , wherein the interlayer includes a nonmagnetic material having a hexagonal close-packed crystal structure whose C-axis orients in the thickness direction of the interlayer.
5. The magnetic recording medium according to claim 1 , wherein the interlayer is made of a material containing Ru or a material containing a RuX 2 alloy, where X is Co, Cr, W or Re.
6. The magnetic recording medium according to claim 1 , wherein the nonmagnetic granular layer has a thickness not less than 2.0 nm but not more than 3.0 nm.
7. The magnetic recording medium according to claim 1 , wherein the nonmagnetic grains in the nonmagnetic granular layer are made of CoCr.
8. The magnetic recording medium according to claim 1 , wherein, in the magnetic granular layer, the magnetic grains are made of at least one alloy selected from CoCr, CoCrPt, CoCrPtCu, CoCrPtB and CoCrPtBCu, and
the nonmagnetic material is an oxide or a nitride containing at least one material selected from Si, Ti, Cr, Ta, Zr, W and Nb.
9. An information storage apparatus, comprising:
a magnetic recording medium including:
a nonmagnetic granular layer that has a granular structure in which a plurality of nonmagnetic grains made of a nonmagnetic material are separated from one another by a Cr oxide, and
a magnetic granular layer that is formed on the nonmagnetic granular layer and has a granular structure in which a plurality of magnetic grains made of a magnetic material are separated from one another by a nonmagnetic material; and
an interlayer made of a nonmagnetic material;
a soft magnetic underlayer made of a soft magnetic material; and
an underlayer that is formed on the soft magnetic underlayer, and is made of a nonmagnetic material having a face-centered cubic lattice crystal structure, and having a surface on which a [1,1,1] plane appears,
wherein the nonmagnetic granular layer is formed on the interlayer, and
wherein the interlayer is formed on the underlayer, and
a head that records information into the nonmagnetic granular layer of the magnetic recording medium.
10. The information storage apparatus according to claim 9 , wherein the magnetic granular layer is formed by growing the magnetic grains on the nonmagnetic grains in the nonmagnetic granular layer.
11. The information storage apparatus according to claim 9 , wherein the nonmagnetic granular layer has, as the nonmagnetic grains, nonmagnetic grains of a hexagonal close-packed crystal structure whose C-axis orients in the thickness direction of the nonmagnetic granular layer.
12. The information storage apparatus according to claim 9 , wherein the interlayer includes a nonmagnetic material having a hexagonal close-packed crystal structure whose C-axis orients in the thickness direction of the interlayer.
13. The information storage apparatus according to claim 9 , wherein the interlayer is made of a material containing Ru or a material containing a RuX 2 alloy, where X is Co, Cr, W or Re.
14. The information storage apparatus according to claim 9 , wherein the nonmagnetic granular layer has a thickness not less than 2.0 nm but not more than 3.0 nm.
15. The information storage apparatus according to claim 9 , wherein the nonmagnetic grains in the nonmagnetic granular layer are made of CoCr.
16. The information storage apparatus according to claim 9 , wherein, in the magnetic granular layer, the magnetic grains are made of at least one alloy selected from CoCr, CoCrPt, CoCrPtCu, CoCrPtB and CoCrPtBCu, and
the nonmagnetic material is an oxide or a nitride containing at least one material selected from Si, Ti, Cr, Ta, Zr, W and Nb.