Ruthenium-aluminum underlayer for magnetic recording media

1. A magnetic recording medium, comprising:

a non-magnetic substrate; an oxidized NiP layer on the non-magnetic substrate;

a B2-structured ruthenium-aluminum-containing underlayer comprising a (200) crystallographic orientation; and

a magnetic layer comprising a Co(11.0) crystallographic orientation, wherein the non-magnetic substrate is mechanically textured and OR-Mrt of the magnetic recording medium is more than about 1.05, thereby the magnetic recording medium is an oriented medium.

2. The magnetic recording medium of claim 1 , wherein the ruthenium-aluminum-containing underlayer comprises RuAl and Ru is in a range from about 45 to about 51.5 atomic percent.

3. The magnetic recording medium of claim 1 , wherein the non-magnetic substrate is non-metallic.

4. The magnetic recording medium of claim 1 , wherein the non-magnetic substrate is an Al-alloy substrate comprising electrolessly plated NiP, wherein the surface of the NiP film is oxidized.

5. The magnetic recording medium of claim 1 , further comprising a chromium-containing second underlayer disposed between the ruthenium-aluminum-containing underlayer and the magnetic layer.

6. The magnetic recording medium of claim 3 , wherein the oxidized NiP film comprises a phosphorus content in a range of about 12 to about 50 atomic percent and an oxygen content in a range of about 0.5 to about 50 atomic percent in the top 50 Å of the oxidized NiP film.

7. The magnetic recording medium of claim 6 , wherein the oxidized NiP film has a thickness of about 50-200,000 Å.

8. The magnetic recording medium of claim 1 , wherein the magnetic layer comprises an alloy material selected from the group consisting of CoCrPtB, CoCrPtBTa, CoCrPtBTaNb, CoCrPt, CoCrNi, CoCrPtTa, CoCrPtTaNb, and CoCrTa.

9. The magnetic recording medium of claim 1 , wherein the ruthenium-aluminum-containing underlayer has a thickness of about 50-800 Å.

10. A method of making a magnetic recording medium comprising:

providing a non-magnetic substrate; depositing an oxidized NiP layer on the non-magnetic substrate;

depositing a B-2 structured ruthenium-aluminum-containing underlayer comprising a (200) crystallographic orientation on the non-magnetic substrate; and

depositing a magnetic layer comprising a Co(11.0) crystallographic orientation on the B-2 structured ruthenium-aluminum-containing underlayer, wherein the non-magnetic substrate is mechanically textured and OR-Mrt of the magnetic recording medium is more than about 1.05, thereby the magnetic recording medium is an oriented medium.

11. The method of claim 10 , wherein the ruthenium-aluminum underlayer comprises from about 45 to about 51.5 atomic percent ruthenium.

12. The method of claim 10 , further comprising depositing a chromium-containing second underlayer between the RuAl-containing underlayer and the magnetic layer.

13. The method of claim 10 , further comprising depositing a CoCr-containing intermediate layer between the RuAl-containing underlayer and the magnetic layer.

14. The method of claim 10 , wherein the magnetic layer comprises an alloy material selected from the group consisting of CoCrPtB, CoCrPtBTa, CoCrPtBTaNb, CoCrPt, CoCrNi, CoCrPtTa, CoCrPtTaNb, and CoCrTa.

15. The method of claim 10 , wherein the ruthenium-aluminum-containing underlayer has a thickness of about 50 Å to about 800 Å.

16. The method of claim 10 , wherein the oxidized NiP layer is sputter deposited.

17. The method of claim 10 , further comprising electroless plating of the non-magnetic substrate with a NiP layer, then oxidizing and mechanical texturing the surface of the NiP layer, wherein the non-magnetic substrate is an Al-alloy substrate.

18. The method of claim 16 , wherein the oxidized NiP layer comprises a phosphorous content of from about 12 at. % to about 50 at. %, and an oxygen content of from about 0.5 at. % to about 50 at. % in the top 50 Å of the oxidized NiP layer.