High damping cap layer for magnetic recording media
View Patent ↗A recording medium having improved signal-to-noise ratio (SNR) capabilities includes a cap layer over the recording layer, where the cap layer has a magnetic damping constant greater than 0.03, such as by using a FeHo cap layer. One mechanism for increasing the SNR is by reducing the switching field distribution. Such a medium is particularly useful in the context of heat-assisted magnetic recording (HAMR).
1. A recording medium comprising:
a substrate;
an adhesion layer over said substrate;
an intermediate layer over said adhesion layer;
a magnetic recording layer over said substrate, said adhesion layer and said intermediate layer;
a cap layer on said magnetic recording layer, said cap layer comprising a material having a magnetic damping constant greater than 0.03;
an overcoat layer over said cap layer; and
a lubricant layer over said overcoat layer.
2. The recording medium of claim 1 , wherein said cap layer comprises a material having a magnetic damping constant of about 0.2.
3. The recording medium of claim 1 , wherein said cap layer comprises a material having higher magnetic damping than Fe.
4. The recording medium of claim 1 , wherein said cap layer comprises a lanthanide element.
5. The recording medium of claim 1 , wherein said cap layer comprises FeHo.
6. The recording medium of claim 1 , wherein said cap layer is a semi-crystalline structure.
7. The recording medium of claim 1 , wherein said cap layer comprises Ho at approximately 20 atomic percent or less.
8. The recording medium of claim 1 , wherein said cap layer has a thickness less than approximately 5 nm.
9. The recording medium of claim 1 , wherein said cap layer is exchange coupled with said magnetic recording layer comprising FePt.
10. The recording medium of claim 1 , wherein said cap layer and said magnetic recording layer are configured to reduce the switching field distribution of said magnetic recording layer.
11. The recording medium of claim 1 , wherein said magnetic damping constant is determined using a ferromagnetic resonance technique.
12. A data storage device comprising:
a heat-assisted magnetic recording (HAMR) disk medium rotatably mounted on a spindle, said HAMR disk medium comprising:
a substrate;
an adhesion layer over said substrate;
an intermediate layer over said adhesion layer;
a magnetic recording layer over said substrate, said adhesion layer and said intermediate layer;
a cap layer on said magnetic recording layer, said cap layer comprising a material having a magnetic damping constant greater than 0.003;
an overcoat layer over said cap layer; and
a lubricant layer over said overcoat layer;
a heat-assisted magnetic recording (HAMR) head slider comprising a magnetic write head configured to write to said HAMR disk medium;
a laser module coupled with said slider; and
a voice coil motor configured to move said HAMR head slider to access portions of said HAMR disk medium.
13. The data storage device claim 12 , wherein said cap layer of said HAMR disk medium comprises a material having a magnetic damping constant of about 0.2.
14. The data storage device claim 12 , wherein said cap layer of said HAMR disk medium comprises a lanthanide.
15. The data storage device of claim 12 , wherein said cap layer of said HAMR disk medium comprises FeHo.
16. The data storage device of claim 12 , wherein said magnetic damping constant is determined using a ferromagnetic resonance technique.
17. A method of manufacturing a recording medium, the method comprising:
forming a magnetic recording layer on a substrate; and
forming a cap layer on and exchange coupled with said magnetic recording layer, said cap layer comprising a material having a magnetic damping constant greater than 0.03;
wherein said cap layer and said magnetic recording layer are formed to reduce the switching field distribution of said magnetic recording layer.
18. The method of claim 17 , wherein forming said cap layer comprises forming a cap layer comprising FeHo.
19. The method of claim 17 , wherein forming said magnetic recording layer comprises forming a magnetic recording layer of FePt, and wherein forming said cap layer comprises forming a cap layer comprising a material having a magnetic damping constant greater than 0.003.
20. A recording medium comprising:
a substrate;
a magnetic recording layer over said substrate; and
a cap layer on said magnetic recording layer, said cap layer comprising a material having a magnetic damping constant greater than 0.03;
wherein said cap layer and said magnetic recording layer are configured to reduce the switching field distribution of said magnetic recording layer.
21. A data storage device comprising:
a heat-assisted magnetic recording (HAMR) disk medium rotatably mounted on a spindle, said HAMR disk medium comprising:
a substrate;
a magnetic recording layer on said substrate; and
a cap layer on said magnetic recording layer, said cap layer comprising a material having a magnetic damping constant greater than 0.003;
wherein said cap layer and said magnetic recording layer are configured to reduce the switching field distribution of said magnetic recording layer;
a heat-assisted magnetic recording (HAMR) head slider comprising a magnetic write head configured to write to said HAMR disk medium;
a laser module coupled with said slider; and
a voice coil motor configured to move said HAMR head slider to access portions of said HAMR disk medium.