Selective annealing of magnetic recording films
Magnetic films are annealed by radio frequency (RF) radiation. During the RF annealing process, the layers may be subjected to a magnetic field in order to control their anisotropy axes. The RF annealed layers are useful for applications such as longitudinal and perpendicular magnetic recording layers of magnetic data storage media.
1. A method of annealing a layer of magnetic recording material, the method comprising:
providing a layer of magnetic recording material; and
annealing the layer with radio frequency radiation which inductively heats the layer of magnetic recording material.
2. The method of claim 1 , wherein the layer of magnetic recording material comprises nanoparticles having an average size of less than about 50 nm.
3. The method of claim 1 , wherein the layer of magnetic recording material is provided by chemical deposition.
4. The method of claim 1 , wherein the layer of magnetic recording material is provided by sputtering.
5. The method of claim 1 , wherein the annealed layer comprises Fe, Co, Pt, Pd, Cr, Ta, Cu, Ag and/or Au.
6. The method of claim 1 , wherein the annealed layer comprises FePt, FePd, CoPt and/or CoPd.
7. The method of claim 1 , wherein the annealed layer comprises FePt.
8. The method of claim 1 , wherein the annealed layer comprises CoCrX where X is Pt, Pd, Ta, Nb, B and/or O.
9. The method of claim 1 , wherein the annealed layer comprises multilayers of Fe/Pt, Fe/Pd, Co/Pt and/or Co/Pd.
10. The method of claim 1 , wherein the annealed layer has a thickness of less than 500 nm.
11. The method of claim 1 , wherein the radio frequency is from about 100 MHz to about 100 GHz.
12. The method of claim 1 , wherein the radio frequency is from about 1 to about 20 GHz.
13. The method of claim 1 , wherein the radio frequency radiation is applied to the layer of magnetic recording material for a time of less than about 60 seconds.
14. The method of claim 1 , wherein the radio frequency radiation is applied to the layer of magnetic recording material for a time of from about 0.1 to about 40 seconds.
15. The method of claim 1 , wherein the layer of magnetic recording material is heated to a temperature of from about 200 to about 900° C. during the annealing step.
16. The method of claim 1 , wherein the layer of magnetic recording material is converted to an L1 0 microstructure during the annealing step.
17. The method of claim 1 , further comprising applying a magnetic field to the layer of magnetic recording material during the annealing step.
18. The method of claim 17 , wherein the magnetic field is applied in a direction substantially parallel with a plane of the layer of magnetic recording material.
19. The method of claim 17 , wherein the magnetic field is applied in a direction substantially perpendicular to a plane of the layer of magnetic recording material.
20. The method of claim 1 , wherein the layer of magnetic recording material is provided on a substrate comprising glass, silicon, ceramic, quartz, NiP and/or plastic.
21. The method of claim 1 , wherein the layer of magnetic recording material is deposited on an intermediate layer of material, and the intermediate layer is heated by the radio frequency radiation.
22. The method of claim 21 , wherein the intermediate layer is a seed layer.
23. The method of claim 1 , wherein the layer of magnetic recording material is provided on a substrate, and the layer of magnetic recording material is heated to a higher temperature than the substrate by the radio frequency radiation.