Single layer small grain size FePT:C film for heat assisted magnetic recording media
View Patent ↗FePt-based heat assisted magnetic recording (HAMR) media comprising a thick granular FePt:C magnetic recording layer capable of maintaining a single layer film having desirable magnetic properties. According to one embodiment, the thick granular FePt:C magnetic recording layer comprises a plurality of carbon doped FePt alloy columnar grains, where the plurality of carbon doped FePt alloy columnar grains comprise a carbon gradient along the thickness of the hard magnetic recording layer.
1. A method of manufacturing a recording medium, comprising:
forming a soft magnetic underlayer;
forming a hard magnetic recording layer over the soft magnetic underlayer, wherein forming the hard magnetic record layer comprises:
depositing a first sub-layer over the soft magnetic underlayer, the first sub-layer comprising a first carbon doped FePt alloy; and
depositing a second sub-layer over the first sub-layer, the second sub-layer comprising a second carbon doped FePt alloy with a different carbon content by at % than the first carbon doped FePt alloy; and
forming a soft magnetic layer over the hard magnetic recording layer, the soft magnetic layer comprising a CoFe or CoCr based soft magnetic alloy,
wherein the hard magnetic recording layer comprises a plurality of carbon doped FePt alloy columnar grains, each of the plurality of carbon doped FePt alloy columnar grains comprising a carbon gradient along a thickness of the hard magnetic recording layer, wherein the different carbon content of the first and second sub-layers results, at least in part, in the carbon gradient.
2. The method of claim 1 , wherein the first sub-layer has 40 at. % carbon.
3. The method of claim 2 , wherein the second sub-layer has 20 at. % carbon.
4. The method of claim 1 , wherein the hard magnetic recording layer is formed through a sputtering process, the sputtering process comprising first and second sputtering operations, wherein the first sputtering operation forms the first sub-layer and wherein the second sputtering operation forms the second sub-layer.
5. The method of claim 4 , wherein the first sputtering operation uses a first sputtering chamber containing the first carbon doped FePt alloy for the first sub-layer, and wherein the second sputtering operation uses a second sputtering chamber containing the second carbon doped FePt alloy for the second sub-layer.
6. The method of claim 4 , wherein the sputtering process uses a pressure range between 2 mT and 100 mT.
7. The method of claim 1 , wherein the carbon gradient is such that carbon content within the hard magnetic recording layer is greater closer to the soft magnetic underlayer.
8. The method of claim 1 , wherein the carbon gradient is such that carbon content within the hard magnetic recording layer is greater away from the soft magnetic underlayer.
9. The method of claim 1 , wherein the thickness of the hard magnetic recording layer is more than 5 nm.
10. The method of claim 1 , wherein the FePt alloy in the carbon doped FePt alloy columnar grains is a FePtX alloy, where X comprises Ag, Au, B, Cu, Ir, Nb, Ni, Ti, W, or Zr.
11. The method of claim 1 , wherein the thickness of the plurality of carbon doped FePt alloy columnar grains is more than 5 nm.