Perpendicular magnetic recording medium and method of manufacturing the same
View Patent ↗A perpendicular magnetic recording medium 100 has, over a substrate, at least a magnetic recording layer 122 with a granular structure in which nonmagnetic grain boundaries are formed between magnetic grains continuously grown into a columnar shape. The magnetic grains of the magnetic recording layer 122 contain Co, Cr, and Pt. The magnetic recording layer 122 contains at least one oxide selected from a group A including SiO 2 , TiO 2 , and Cr 2 O 3 , at least one oxide selected from a group B consisting of oxides each having a larger Gibbs free energy ΔG than the group A, and a reducing agent adapted to reduce the oxides of the group B.
1. A perpendicular magnetic recording medium comprising:
a substrate,
at least a magnetic recording layer with a granular structure in which a nonmagnetic grain boundary is formed between magnetic grains continuously grown into a columnar shape,
wherein said magnetic grains contain Co, Cr, and Pt, and said magnetic recording layer contains
at least one oxide selected from a group A comprising SiO 2 , TiO 2 , and Cr 2 O 3 ,
at least one oxide selected from a group B consisting of oxides each having a larger Gibbs free energy ΔG than said group A, and
at least one oxide selected from a group C consisting of oxides each having a smaller Gibbs free energy ΔG than said group B, and
wherein said magnetic recording layer is made of CoCrPt—TiO 2 —SiO 2 —Co 3 O 4 —SiO.
2. A perpendicular magnetic recording medium manufacturing method comprising:
forming a magnetic recording layer over a substrate by the use of a target containing a metal containing Co, Cr, and Pt, at least one oxide selected from a group A, which is operative to form grain boundaries, comprising SiO 2 , TiO 2 , and Cr 2 O 3 , at least one oxide selected from a group B, which is operative to supplement oxygen deficiencies, consisting of oxides each having a larger Gibbs free energy ΔG than said group A, and at least one oxide selected from a group C, which is operative as a reducing agent, consisting of oxides each having a smaller Gibbs free energy ΔG than said group B,
wherein said magnetic recording layer is made of CoCrPt—TiO 2 —SiO 2 —Co 3 O 4 —SiO.
3. A perpendicular magnetic recording medium comprising:
a substrate,
at least a magnetic recording layer with a granular structure in which a nonmagnetic grain boundary is formed between magnetic grains continuously grown into a columnar shape,
wherein said magnetic grains contain Co, Cr, and Pt, and said magnetic recording layer contains
at least one oxide selected from a group A, which is operative to form grain boundaries, comprising SiO 2 , TiO 2 , and Cr 2 O 3 ,
at least one oxide selected from a group B, which is operative to supplement oxygen deficiencies, consisting of oxides each having a larger Gibbs free energy ΔG than said group A, and
at least one oxide selected from a group C, which is operative as a reducing agent, consisting of oxides each having a smaller Gibbs free energy ΔG than said group B,
wherein the oxides of said group B are each at least one compound selected from a group comprising CoO, Co 3 O 4 , CuO, Ag 2 O, and WO 3 , and
wherein Co 3 O 4 is used in Group B and the amount of Co 3 O 4 is 2 mol % or less.
4. The perpendicular magnetic recording medium of claim 1 , wherein the amount of Co 3 O 4 is 2 mol % or less.
5. The perpendicular magnetic recording medium according to claim 3 , wherein the oxides of said group C are each at least one compound selected from a group comprising SiO, TiO, and Cr 2 O 2 , and Cr 3 O 3 .
6. The perpendicular magnetic recording medium manufacturing method according to claim 2 , wherein the oxides of said group C are each at least one compound selected from a group comprising SiO, TiO, and Cr 2 O 2 , and Cr 3 O 3 .
7. The perpendicular magnetic recording medium manufacturing method according to claim 2 , wherein the oxides of said group B are each at least one compound selected from a group comprising CoO, Co 3 O 4 , CuO, Ag 2 O, and WO 3 .