Perpendicular magnetic recording media and methods for producing the same
View Patent ↗[Problem] An object is to provide a perpendicular magnetic recording medium that can realize both improvement in crystal orientation and refinement of crystal grain size and can achieve a higher recording density and a higher SN ratio, and a method of manufacturing the same. [Solution] A perpendicular magnetic recording medium 100 of the present invention is a perpendicular magnetic recording medium 100 having a base plate 100 , and a laminate film including a first ground layer 150 a provided on the base plate 100 , a second ground layer 150 b provided on the first ground layer 150 a , and a main recording layer 160 provided on the second ground layer 150 b and containing a magnetic material having a granular structure, wherein the magnetic material which constitutes the main recording layer 160 contains a CoCrPt alloy, and a material which constitutes the second ground layer 150 b contains an Ru—Co oxide alloy.
1. A perpendicular magnetic recording medium comprising:
a base plate, and
a laminate film including a first ground layer provided on the base plate, a second ground layer provided on the first ground layer, and a magnetic layer provided on the second ground layer and containing a magnetic material having a granular structure,
wherein the magnetic layer contains a CoCrPt alloy, and the second ground layer consists of Ru-xCo 3 O 4 , where x ranges from 0.2 mol to 5 mol,
wherein the first ground layer consists of Ru and is thicker than the second ground layer,
wherein a film thickness of the second ground layer is 8 nm-15nm,
wherein a total film thickness of the first and second ground layers is 11 nm-40 nm, and
wherein the first ground layer is formed under a first gas pressure, the second ground layer is formed under a second gas pressure, and the second gas pressure is higher than the first gas pressure.
2. The perpendicular magnetic recording medium according to claim 1 , wherein the film thickness of the second ground layer ranges from 8 nm to less than 10 nm.
3. The perpendicular magnetic recording medium according to claim 1 , wherein the second ground layer has a granular structure with voids formed between crystal grains that provides separation of the crystal grains and that results from formation under the condition of an Ar atmosphere at a gas pressure in the range of 3 Pa to 10 Pa, being filled with an oxide.
4. The perpendicular magnetic recording medium according to claim 1 , further comprising a preliminary ground layer disposed between the base and the first ground layer.
5. The perpendicular magnetic recording medium according to claim 4 , wherein the preliminary ground layer has a thickness in a range from 1 nm to 20 nm.
6. The perpendicular magnetic recording medium according to claim 4 , wherein the preliminary ground layer comprises Cu, Pt, Pd, Co, Hf or an alloy containing these materials as a main component and added with at least one of V, Cr, Mo and W.
7. The perpendicular magnetic recording medium according to claim 6 , wherein the preliminary ground layer comprises Co.
8. The perpendicular magnetic recording medium according to claim 1 , wherein x ranges from 0.2 mol to less than 3 mol.
9. The perpendicular magnetic recording medium according to claim 1 , wherein the film thickness of the second ground layer is 10 nm-15 nm.
10. The perpendicular magnetic recording medium according to claim 1 , wherein x ranges from 0.2 mol to 1.25 mol.
11. The perpendicular magnetic recording medium according to claim 1 , wherein x ranges from 0.2 mol to 0.6 mol.