Heat-assisted magnetic recording (HAMR) medium with optical-coupling multilayer between the recording layer and heat-sink layer
A heat-assisted magnetic recording (HAMR) disk has a magnetic recording layer (typically a FePt chemically-ordered alloy), a seed-thermal barrier layer (typically MgO) below the recording layer, a heat-sink layer, and an optical-coupling multilayer of alternating plasmonic and non-plasmonic materials between the heat-sink layer and the seed-thermal barrier layer. Unlike a heat sink layer, the multilayer has very low in-plane and out-of-plane thermal conductivity and thus does not function as a heat sink layer. The multilayer's low thermal conductivity allows the multilayer to also function as a thermal barrier. Due to the plasmonic materials in the multilayer it provides excellent optical coupling with the near-field transducer (NFT) of the HAMR disk drive.
1. A heat-assisted magnetic recording medium comprising:
a substrate;
a heat-sink layer on the substrate;
a magnetic recording layer comprising a chemically-ordered alloy selected from a FePt alloy and a CoPt alloy;
a seed-thermal barrier layer for the recording layer, wherein the recording layer is on and in contact with the seed-thermal barrier layer; and
a multilayer comprising alternating layers of a plasmonic material and a non-plasmonic material, the multilayer being between the heat-sink layer and the seed-thermal barrier layer.
2. The medium of claim 1 wherein the plasmonic material is selected from Au, Ag, Cu and Rh.
3. The medium of claim 1 wherein the non-plasmonic material is selected from a RuAl alloy, a NiTa alloy, a CrTa alloy and a nitride of Cr, V, W or Mo.
4. The medium of claim 1 wherein each of the layers of plasmonic and non-plasmonic material has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm.
5. The medium of claim 1 wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.
6. The medium of claim 1 wherein the heat-sink layer is formed of material selected from Cr, W, Mo and their alloys.
7. The medium of claim 1 wherein the seed-thermal barrier layer is selected from MgO and MTO.
8. The medium of claim 1 wherein a layer of non-plasmonic material in the multilayer is on and in contact with the heat-sink layer.
9. The medium of claim 1 wherein the magnetic recording layer further comprises a substantially chemically-ordered alloy comprising Pt and an element selected from Fe and Co, and a segregant selected from one or more of C, SiO 2 , TiO 2 , TaO x , ZrO 2 , SiC, SiN, TiC, TiN, B, BC and BN.
10. The medium of claim 1 wherein the multilayer is on and in contact with the heat sink layer and the seed-thermal barrier layer is on and in contact with the multilayer.
11. The medium of claim 1 wherein the seed-thermal barrier layer comprises first and second films, wherein the multilayer is between the first and second films, the first film is on and in contact with the heat-sink layer, the second film is on and in contact with the multilayer, and the recording layer is on and in contact with the second film.
12. The medium of claim 11 wherein each of the first and second seed-thermal barrier layer films is selected from MgO and MTO.
13. The medium of claim 11 wherein the plasmonic material is selected from Au, Ag, Cu and Rh, and the non-plasmonic material is selected from a RuAl alloy, a NiTa alloy, a CrTa alloy and a nitride of Cr, V, W or Mo.
14. A heat assisted magnetic recording (HAMR) disk drive comprising:
the medium according to claim 1 wherein said medium is a rotatable HAMR disk; and
a carrier maintained near the magnetic recording layer of the disk and supporting a near-field transducer.
15. A heat-assisted magnetic recording (HAMR) disk comprising:
a disk substrate;
a heat-sink layer on the substrate;
a multilayer comprising alternating layers of a plasmonic material and a non-plasmonic material on the heat-sink layer, the plasmonic material being selected from Au, Ag, Cu and Rh, and the non-plasmonic material being selected from a RuAl alloy, a NiTa alloy, a CrTa alloy and a nitride of Cr, V, W or Mo;
a seed-thermal barrier layer selected from MgO and MTO on and in contact with the multilayer; and
a magnetic recording layer comprising a chemically-ordered alloy selected from a FePt alloy and a CoPt alloy on and in contact with the seed-thermal barrier layer.
16. The disk of claim 15 wherein each of the layers of plasmonic and non-plasmonic material has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 20 nm.
17. A heat assisted magnetic recording (HAMR) disk drive comprising:
the disk according to claim 15 ; and
a gas-bearing slider maintained near the magnetic recording layer of the disk and supporting a near-field transducer.
18. A heat-assisted magnetic recording (HAMR) disk comprising:
a disk substrate;
a heat-sink layer on the substrate;
a first seed-thermal barrier film selected from MgO and MTO on the heat-sink layer;
a multilayer comprising alternating layers of a plasmonic material and a non-plasmonic material on the first seed-thermal film, the plasmonic material being selected from Au, Ag, Cu and Rh, and the non-plasmonic material being selected from a RuAl alloy, a NiTa alloy, a CrTa alloy and a nitride of Cr, V, W or Mo;
a second seed-thermal barrier film selected from MgO and MTO on and in contact with the multilayer; and
a magnetic recording layer comprising a chemically-ordered alloy selected from a FePt alloy and a CoPt alloy on and in contact with the second seed-thermal barrier film.
19. The disk of claim 18 wherein each of the layers of plasmonic and non-plasmonic material has a thickness greater than or equal to 0.5 nm and less than or equal to 2 nm and wherein the multilayer has a thickness greater than or equal to 3 nm and less than or equal to 15 nm.
20. A heat assisted magnetic recording (HAMR) disk drive comprising:
the disk according to claim 18 ; and
a gas-bearing slider maintained near the magnetic recording layer of the disk and supporting a near-field transducer.