Energy assisted magnetic recording medium capable of suppressing high DC readback noise
View Patent ↗A perpendicular magnetic recording (PMR) disk used in energy assisted magnetic recording drives is described. The PMR disk includes a substrate, a magnetic recording layer disposed above the substrate, an exchange coupling layer disposed above the magnetic recording layer, and a capping layer disposed above the exchange coupling layer. The capping layer has a Curie temperature greater than the Curie temperature of the magnetic recording layer.
1. A perpendicular magnetic recording (PMR) disk, comprising:
a substrate;
a magnetic recording layer disposed above the substrate, wherein the magnetic recording layer has a first Curie temperature;
an exchange coupling layer disposed above the magnetic recording layer; and
a capping layer disposed above the exchange coupling layer, wherein the capping layer has a second Curie temperature being greater than the first Curie temperature of the magnetic recording layer, wherein the capping layer remains magnetized during a refreezing process of a write operation.
2. The perpendicular magnetic recording disk of claim 1 , wherein the magnetic recording layer has a first magnetic anisotropy, the capping layer has a second magnetic anisotropy being less than the first magnetic anisotropy of the magnetic recording layer.
3. The perpendicular magnetic recording disk of claim 1 , the magnetic recording layer has a first lateral exchange coupling, the capping layer has a second lateral exchange coupling being greater than the first lateral exchange coupling of the magnetic recording layer.
4. The perpendicular magnetic recording disk of claim 1 , wherein the magnetic recording layer has a first packing fraction, the capping layer has a second packing fraction being greater than the first packing fraction of the magnetic recording layer.
5. The perpendicular magnetic recording disk of claim 1 , wherein the first Curie temperature is in a range of 500 degrees Kelvin to 800 degrees Kelvin.
6. The perpendicular magnetic recording disk of claim 5 , wherein the second Curie temperature is greater than the first Curie temperature by an amount being in a range of 20 degrees Kelvin to 600 degrees Kelvin.
7. The perpendicular magnetic recording disk of claim 6 , wherein the first Curie temperature is approximately 645 degrees Kelvin and the second Curie temperature is approximately 745 degrees Kelvin.
8. The perpendicular magnetic recording disk of claim 4 , wherein the second packing fraction is greater than 60%.
9. The perpendicular magnetic recording disk of claim 1 , wherein the capping layer has a thickness in a range of 1 nanometer (nm) to 12 nm.
10. The perpendicular magnetic recording disk of claim 9 , wherein the exchange coupling layer has a thickness in a range of 0.3 nm to 2 nm.
11. The perpendicular magnetic recording disk of claim 1 , wherein magnetic recording layer comprises an ordered inter-metallic L10 alloy.
12. The perpendicular magnetic recording disk of claim 1 , wherein the exchange coupling layer comprises a ruthenium (Ru) or a cobalt-ruthenium (RuCo) alloy.
13. The perpendicular magnetic recording disk of claim 1 , wherein the capping layer comprises an iron-type alloy (FeX), a cobalt-platinum-type alloy (CoPtX), an iron-platinum-type alloy (FePtX), or a cobalt-type alloy (CoX).
14. An energy assisted magnetic recording (EAMR) drive, comprising:
a perpendicular magnetic recording (PMR) disk comprising:
a substrate;
a magnetic recording layer disposed above the substrate, the magnetic recording layer having a first Curie temperature;
an exchange coupling layer disposed above the magnetic recording layer; and
a capping layer disposed above the exchange coupling layer, the capping layer having a second Curie temperature being greater than the first Curie temperature of the magnetic recording layer, wherein the capping layer remains magnetized during a refreezing process of a write operation; and
an energy source to generate a thermal spot on the PMR disk.
15. The EAMR drive of claim 14 , wherein the EAMR drive is a heat assisted magnetic recording (HAMR) drive.
16. The EAMR drive of claim 14 , wherein the second Curie temperature is greater than the first Curie temperature in a range of 20 degrees Kelvin to 600 degrees Kelvin.
17. The EAMR drive of claim 16 , wherein the thermal spot has a peak temperature in a range of 500 degrees Kelvin to 900 degrees Kelvin.
18. The EAMR drive of claim 17 , wherein the capping layer remains magnetized in response to the thermal spot to provide a field reference to the magnetic recording layer.