Magnetic recording medium utilizing adjacent underlayer and magnetic layer having particular compositions, magnetic storage apparatus, and method of manufacturing magnetic recording medium
A magnetic recording medium includes a substrate, an underlayer provided above the substrate, and a magnetic layer provided on and in contact with the underlayer. The underlayer includes a compound represented by a general formula MgO (1-x) , where x falls within a range of 0.07 to 0.25. The magnetic layer includes an alloy having a L1 0 structure, and the alloy having the L1 0 structure includes one or more elements selected from a group consisting of Al, Si, Ga, and Ge.
1. A magnetic recording medium comprising:
a substrate;
an underlayer including an upper underlayer provided above the substrate; and
a first magnetic layer provided on and in contact with the upper underlayer,
wherein the upper underlayer includes a compound represented by a general formula MgO (1-x) , where x falls within a range of 0.07 to 0.25,
wherein the first magnetic layer includes an alloy having a L1 0 structure, and
wherein the alloy having the L1 0 structure includes one or more elements selected from a group consisting of Al, Si, Ga, and Ge.
2. The magnetic recording medium as claimed in claim 1 , wherein the alloy having the L1 0 structure further includes Fe or Co, and Pt.
3. The magnetic recording medium as claimed in claim 1 , wherein a content of the one or more elements selected from the group consisting of Al, Si, Ga, and Ge in the alloy having the L1 0 structure is in a range of 2 mol % to 20 mol %.
4. The magnetic recording medium as claimed in claim 1 , wherein a content of the one or more elements selected from the group consisting of Al, Si, Ga, and Ge in the alloy having the L1 0 structure is in a range of 2.5 mol % to 10 mol %.
5. The magnetic recording medium as claimed in claim 1 , wherein
the upper the underlayer further includes one or more lower underlayers provided under the upper underlayer,
wherein each of the one or more lower underlayers includes a material that makes the first magnetic layer (001) oriented.
6. The magnetic recording medium as claimed in claim 5 , wherein the material included in each of the one or more lower underlayers is selected from a group consisting of (100) oriented W, Cr, Cr alloys having a BCC structure, and alloys having a B2 structure.
7. The magnetic recording medium as claimed in claim 6 , wherein the Cr alloys having the BCC structure include CrMn alloys, CrMo alloys, CrW alloys, CrV alloys, CrTi alloys, and CrRu alloys.
8. The magnetic recording medium as claimed in claim 6 , wherein the alloys having the B2 structure include RuAl alloys, and NiAl alloys.
9. The magnetic recording medium as claimed in claim 1 , wherein
the first magnetic layer further includes a grain boundary segregation material, and has a granular structure, and
the grain boundary segregation material includes one or more elements selected from a group consisting of nitrides including VN, BN, SiN, and TiN, carbides including C and VC, and borides including BN.
10. The magnetic recording medium as claimed in claim 9 , wherein
the underlayer further includes one or more lower underlayers provided under the upper underlayer, and
the one or more lower underlayers includes a material selected from a group consisting of (100) oriented W, Cr, Cr alloys having a BCC structure, and alloys having a B2 structure.
11. The magnetic recording medium as claimed in claim 9 , further comprising:
a plurality of magnetic layers including the first magnetic layer, and one or more second magnetic layers provided on the first magnetic layer,
wherein the one or more second magnetic layers includes an alloy having a L1 0 structure.
12. A magnetic storage apparatus comprising:
the magnetic recording medium according to claim 1 ; and
a magnetic head configured to write information to and read information from the magnetic recording medium.
13. A method of manufacturing the magnetic recording medium according to claim 1 , comprising:
forming the upper underlayer with a sputtering target that includes MgO and a sputtering gas in which hydrogen is added to an inert gas in the range of 1 vol % to 20 vol %.
14. A method of manufacturing the magnetic recording medium according to claim 1 , comprising:
performing a discharge using a sputtering target that includes MgO for 0.5 second or less at a sputtering gas pressure of 1 Pa or higher; and
performing a discharge at a sputtering gas pressure of 0.5 Pa or lower, to form the upper underlayer.