Dual seed layer for magnetic recording media
A magnetic recording medium includes a substrate, a soft magnetic underlayer on the substrate, and a dual seed layer. The dual seed layer includes a first seed layer comprising NiFe at a first concentration, and a second seed layer comprising NiFe at a second concentration different from the first concentration and a segregant. The first seed layer may be on a soft magnetic underlayer and the second seed layer is on the first seed layer. The magnetic recording medium may further include one or more magnetic recording layers on the dual seed layer. The magnetic recording medium with the composition-graded dual seed layer may provide small grain size and good crystallographic texture for layers on the dual seed layer, including the magnetic recording layers.
1. A magnetic recording medium, the magnetic recording medium comprising:
a substrate;
a soft magnetic underlayer on the substrate;
a dual seed layer including:
a first seed layer having a first seed layer thickness and comprising NiFe at a first concentration; and
a second seed layer having a second seed layer thickness and comprising NiFe at a second concentration different from the first concentration and a segregant that comprises an oxide having an oxide concentration, wherein the thicknesses of the first and second seed layers are configured in accordance with a thickness ratio in which the higher the concentration of the oxide in the second seed layer, the thinner the second seed layer thickness is relative to the first seed layer thickness, and wherein the first seed layer is on the soft magnetic underlayer and the second seed layer is on the first seed layer; and
one or more magnetic recording layers on the dual seed layer.
2. The magnetic recording medium of claim 1 , wherein the first seed layer comprises:
Ni with an atomic percentage in a range of 50% to 75%; and
Fe with an atomic percentage in a range of 15% to 35%.
3. The magnetic recording medium of claim 2 , wherein the first seed layer further comprises:
one or more additional metals selected from the group consisting of: W, Al, Cr, Ta, Mo, and combinations thereof.
4. The magnetic recording medium of claim 3 , wherein the one or more additional metals comprise:
W with an atomic percentage in a range of 2% to 12%; and
Al with an atomic percentage in a range of 0.5% to 3%.
5. The magnetic recording medium of claim 2 , wherein the first seed layer is substantially free of oxide.
6. The magnetic recording medium of claim 2 , wherein:
the atomic percentage of one or both of Ni and Fe in the second seed layer is less than the respective atomic percentages of Ni and Fe included in the first seed layer.
7. The magnetic recording medium of claim 6 , wherein the molecular percentage of the oxide is in a range of 0.5% to 8%.
8. The magnetic recording medium of claim 6 , wherein the oxide is selected from the group consisting of: TiO2, SiO2, B2O3, Ta2O5, Cr2O3, MnO, and combinations thereof.
9. The magnetic recording medium of claim 6 , wherein the second seed layer further comprises:
one or more additional metals selected from the group consisting of W, Al, Cr, Ta, Mo, and combinations thereof.
10. The magnetic recording medium of claim 2 , wherein:
the segregant of the second seed layer further comprises one or more metals selected from a group consisting of W, Al, Cr, Ta, Mo, and combinations thereof, and
the atomic percentage of one or both of Ni and Fe in the second seed layer is less than the respective atomic percentages of Ni and Fe included in the first seed layer.
11. The magnetic recording medium of claim 1 , wherein each of the first seed layer and the second seed layer comprises a close-packed crystallographic structure with a close-packed atomic plane parallel to a surface of the substrate.
12. The magnetic recording medium of claim 1 , wherein the one or more magnetic recording layers comprise Co-based magnetic layers with multiple exchange control layers (ECLs).
13. The magnetic recording medium of claim 1 , wherein a total thickness of the first seed layer and the second seed layer is between 2.5 and 6.5 nanometers.
14. A data storage device, comprising:
the magnetic recording medium of claim 1 ; and
a recording head configured to write information to the magnetic recording medium.
15. The magnetic recording medium of claim 1 , further comprising:
an interlayer on the second seed layer; and
an underlayer on the interlayer; and
wherein the one or more magnetic recording layers is on the underlayer.
16. A method for fabricating magnetic recording media, comprising:
providing a substrate;
providing a soft magnetic underlayer (SUL) on the substrate;
providing a first seed layer on the SUL having a first seed layer thickness, the first seed layer comprising NiFe at a first concentration;
providing a second seed layer on the first seed layer, the second seed layer having a second seed layer thickness and comprising NiFe at a second concentration different from the first concentration and a segregant that comprises an oxide having an oxide concentration;
wherein the thicknesses of the first and second seed layers are configured in accordance with a thickness ratio in which the higher the concentration of the oxide in the second seed layer, the thinner the second seed layer thickness is relative to the first seed layer thickness; and
providing one or more magnetic recording layers on the second seed layer.
17. The method of claim 16 , wherein the first seed layer comprises:
Ni with an atomic percentage in a range of 50% to 75%; and
Fe with an atomic percentage in a range of 15% to 35%.
18. The method of claim 17 , wherein the first seed layer further comprises:
one or more additional metals selected from the group consisting of: W, Al, Cr, Ta, Mo, and combinations thereof.
19. The method of claim 17 , wherein the first seed layer is substantially free of oxide.
20. The method of claim 17 , wherein:
the atomic percentage of one or both of Ni and Fe in the second seed layer is less than the respective atomic percentages of Ni and Fe included in the first seed layer.
21. The method of claim 17 , wherein:
the segregant of the second seed layer further comprises one or more metals selected from a group consisting of W, Al, Cr, Ta, Mo, and combinations thereof, and
the atomic percentage of one or both of Ni and Fe in the second seed layer is less than the respective atomic percentages of Ni and Fe included in the first seed layer.
22. The method of claim 17 , wherein each of the first seed layer and the second seed layer comprises a close-packed crystallographic structure with a close-packed atomic plane parallel to a surface of the substrate.
23. The method of claim 16 , further comprising:
providing an interlayer on the second seed layer; and
providing an underlayer on the interlayer; and
wherein the providing the one or more magnetic recording layers on the second seed layer comprises providing the one or more magnetic recording layers on the underlayer.
24. The method of claim 16 , wherein a ratio of the second thickness to the first thickness approaches 1:1 as the oxide concentration in the second seed layer approaches zero.
25. The method of claim 16 , further comprising selecting the first seed layer thickness and selecting the oxide concentration for the second seed layer and then configuring the second layer thickness in accordance with the thickness ratio based on the first seed layer thickness and the selected oxide concentration.