Thin film media with a dual seed layer of RuAI/NiAIB
View Patent ↗A thin film structure for a magnetic thin film recording medium including a dual seed layer of RuAl/NiAlB is disclosed. The use of the RuAl/NiAlB structure provides reduced grain size, an increased Mrt orientation ratio (OR), increased SNR and lower PW50 at higher amplitude. The RuAl and NiAlB seed layers each have a B2 crystallographic structure. The RuAl/NiAlB dual seed layer can be used to obtain an underlayer with a preferred in-plane orientation of (200) and a cobalt alloy magnetic film with the preferred in-plane orientation of (11{overscore ( )}20).
1. A magnetic thin film layer structure comprising:
a layer of RuAl;
a layer of NiAlB epitaxially deposited on the layer of RuAl; and
a ferromagnetic layer structure deposited after the layer of NiAlB.
2. The magnetic thin film layer structure of claim 1 wherein the NiAlB has approximately from 2 to 5 atomic percent boron with the remainder being generally divided between nickel and aluminum.
3. The magnetic thin film layer structure of claim 2 wherein NiAlB has approximately 50 atomic percent nickel, 48 atomic percent aluminum and 2 atomic percent boron.
4. The magnetic thin film layer structure of claim 1 further comprising a substrate and a pre-seed layer of CrTi deposited on the substrate prior to the layer of RuAl.
5. The magnetic thin film layer structure of claim 4 wherein the substrate is circumferentially textured glass.
6. The magnetic thin film layer structure of claim 1 further comprising an underlayer of CrTi deposited on the layer of NiAlB.
7. The magnetic thin film layer structure of claim 1 wherein the ferromagnetic layer structure further comprises a magnetic layer stack including a layer of CoCr and a layer of CoPtCrB separated by a spacer layer.
8. The magnetic thin film layer structure of claim 7 wherein the spacer layer is ruthenium.
9. A magnetic thin film disk comprising:
an amorphous or nanocrystalline pre-seed layer;
a seed layer of RuAl with a B2 crystallographic structure deposited on the pre-seed layer;
a seed layer of NiAlB with a B2 crystallographic structure deposited on the layer of RuAl, the NiAlB having approximately from 2 to 5 atomic percent boron with the remainder being generally divided between nickel and aluminum; and
a ferromagnetic layer structure above the layer of NiAlB.
10. The magnetic thin film disk of claim 9 wherein the seed layer of NiAlB has approximately 2 at. % boron.
11. The magnetic thin film disk of claim 9 further comprising a substrate and wherein the pre-seed layer is CrTi deposited on the substrate.
12. The magnetic thin film disk of claim 9 further comprising an underlayer of CrTi deposited on the layer of NiAlB prior to the ferromagnetic layer structure.
13. The magnetic thin film disk of claim 9 wherein the ferromagnetic layer structure includes is CoPtCrB and is preceded by a spacer layer and a layer of CoCr forming a magnetic layer stack.
14. A magnetic disk drive comprising:
a magnetic transducer including a read head and a write head;
a suspension supporting the magnetic transducer over a magnetic disk; and
the magnetic disk including a dual seed layer comprising a layer RuAl followed by a layer of NiAlB epitaxially deposited onto the layer of RuAl.
15. The magnetic disk drive of claim 14 wherein the layer of NiAlB has approximately from 2 to 5 atomic percent boron with the remainder being generally divided between nickel and aluminum.
16. The magnetic disk drive of claim 15 wherein the layer of NiAlB has approximately 50 atomic percent nickel, 48 atomic percent aluminum and 2 atomic percent boron.
17. The magnetic disk drive of claim 14 wherein the magnetic disk further comprises a circumferentially textured substrate and the magnetic disk has an Mrt orientation ratio greater than one.
18. The magnetic disk drive of claim 14 wherein the magnetic disk further comprises an underlayer of CrTi deposited on the layer of NiAlB.
19. The magnetic disk drive of claim 14 wherein the magnetic disk further comprises a magnetic layer stack deposited after the layer of NiAlB including a layer of CoCr and a layer CoPtCrB separated by a spacer layer.