Heat assisted magnetic recording (HAMR) media having a highly ordered crystalline structure

1. A magnetic recording medium, comprising:

a substrate;

a seed layer positioned above the substrate; and

a magnetic recording layer structure positioned above the seed layer, the magnetic recording layer structure including:

a first magnetic recording layer having a plurality of FePtCu magnetic grains and a first segregant, wherein a pitch between the FePtCu magnetic grains in the first magnetic recording layer is in a range from about 3 nm to 11 nm; and

a second magnetic recording layer positioned above the first magnetic recording layer, the second magnetic recording layer having a plurality of FePt magnetic grains and a second segregant; and

wherein a Curie temperature of the first magnetic recording layer is lower than a Curie temperature of the second magnetic recording layer.

2. The magnetic recording medium as recited in claim 1 , wherein the first segregant and the second segregant are independently selected from a group consisting of: C, SiO 2 , TiO 2 , TaO x , SiC, SiN, TiC, TiN, BN, BC, Cr-oxide, Cr-nitride, MgO, B and combinations thereof.

3. The magnetic recording medium as recited in claim 1 , wherein a thickness of the first magnetic recording layer is in a range from greater than 0 nm to less than or equal to about 3 nm.

4. The magnetic recording medium as recited in claim 1 , wherein a diameter of the FePtCu magnetic grains in the first magnetic recording layer is in a range from about 2 to 10 nm.

5. The magnetic recording medium as recited in claim 1 , wherein an amount of Cu in the FePtCu magnetic grains in the first magnetic recording layer is in a range from about 5 at.% to 20 at.%.

6. The magnetic recording medium as recited in claim 1 , wherein the FePtCu magnetic grains in the first magnetic recording layer further comprise at least one of: Ag, Au, Ni, and Mn.

7. The magnetic recording medium as recited in claim 1 , wherein the FePt magnetic grains in the second magnetic recording layer further comprises Cu, wherein an amount of Cu in the second magnetic recording layer is less than an amount of Cu in the first magnetic recording layer.

8. The magnetic recording medium as recited in claim 1 , wherein a thickness of the second magnetic recording layer is in a range from about 3 nm to 15 nm.

9. The magnetic recording medium as recited in claim 1 , wherein a diameter of the FePt magnetic grains in the second magnetic recording layer is in a range from about 2 to 10 nm.

10. The magnetic recording medium as recited in claim 1 , wherein the second magnetic recording layer does not include Cu.

11. The magnetic recording medium as recited in claim 1 , wherein the magnetic grains of the second magnetic layer are physically characterized by growth directly on the magnetic grains of the first magnetic recording layer.

12. The magnetic recording medium as recited in claim 1 , wherein magnetic grains of the first and second magnetic recording layers form composite magnetic grains extending through the magnetic recording layer structure, wherein a total thickness of the magnetic recording layer structure is at least 6 nm, and wherein the composite magnetic grains have an aspect ratio of at least 1.5.

13. The magnetic recording medium as recited in claim 1 , wherein the seed layer includes MgO.

14. The magnetic recording medium as recited in claim 1 , further comprising a thermal barrier layer positioned above the substrate and below the seed layer.

15. The magnetic recording medium as recited in claim 1 , wherein the magnetic recording layer structure further comprises a third magnetic recording layer positioned above the second magnetic recording layer, the third magnetic layer having a plurality of FePt magnetic grains and a third segregant.

16. The magnetic recording medium as recited in claim 15 , wherein the FePt magnetic grains of the third magnetic recording layer further comprise Cu.

17. The magnetic recording medium as recited in claim 15 , wherein the third magnetic recording layer has a thickness in a range from greater than 0 nm and less than or equal to about 3 nm.

18. A magnetic data storage system, comprising:

at least one magnetic head;

a magnetic recording medium as recited in claim 1 ;

a drive mechanism for passing the magnetic medium over the at least one magnetic head; and

a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head.

19. A magnetic recording medium, comprising:

a substrate;

a seed layer positioned above the substrate; and

a magnetic recording layer structure positioned above the seed layer, the magnetic recording layer structure including:

a first magnetic recording layer having a plurality of FePtCu magnetic grains and a first segregant; and

a second magnetic recording layer positioned above the first magnetic recording layer, the second magnetic recording layer having a plurality of FePt magnetic grains and a second segregant; and

wherein a Curie temperature of the first magnetic recording layer is lower than a Curie temperature of the second magnetic recording layer,

wherein a pitch between the FePt magnetic grains in the second magnetic recording layer is in a range from about 3 nm to 11 nm.

20. A magnetic recording medium, comprising:

a substrate;

a thermal barrier layer positioned above the substrate;

a seed layer positioned above the thermal barrier layer; and

a magnetic recording layer structure positioned directly above and on the seed layer, the magnetic recording layer structure including:

a first magnetic recording layer having a plurality of L1 0 FePt—X magnetic grains and a first segregant, X being selected from a group consisting of: Ag, Cu, Au, Ni, Mn, and combinations thereof; and

a second magnetic recording layer positioned above the first magnetic recording layer, the second magnetic recording layer having a plurality of L1 0 FePt magnetic grains and a second segregant;

wherein a Curie temperature of the first magnetic recording layer is lower than a Curie temperature of the second magnetic recording layer,

wherein an amount of X in the FePt—X magnetic grains in the first magnetic recording layer is between about 5 at % and 20 at.%,

wherein at least one of the following characteristics is present in the magnetic recording layer structure:

a pitch between the L1 0 FePt—X magnetic grains in the first magnetic recording layer is in a range from about 3 nm to 11 nm, and

a pitch between the L1 0 FePt magnetic grains in the second magnetic recording layer in a range from about 3 nm to 11 nm.

21. The magnetic recording medium as recited in claim 20 , wherein the first segregant and the second segregant are independently selected from a group consisting of: C, SiO 2 , TiO 2 , TaO x , SiC, SiN, TiC, TiN, BN, BC, Cr-oxide, Cr-nitride, MgO, B and combinations thereof.

22. The magnetic recording medium as recited in claim 20 , wherein a thickness of the FePt—X magnetic grains in the first magnetic recording layer is in a range from greater than 0 nm to less than or equal to about 3 nm, wherein a thickness of the FePt magnetic grains in the second magnetic recording layer is between in a range from about 3 nm to about 15 nm.

23. The magnetic recording medium as recited in claim 20 , wherein the seed layer includes MgO.

24. The magnetic recording medium as recited in claim 20 , wherein the magnetic recording layer structure further comprises a third magnetic recording layer positioned above the second magnetic recording layer, wherein the third magnetic layer has a plurality of FePt magnetic grains and a third segregant, wherein the FePt magnetic grains of the third magnetic recording layer optionally include an additional element selected from a group consisting of: Ag, Cu, Au, Ni, Mn, and combinations thereof.