Perpendicular magnetic recording media with lateral exchange control layer
A magnetic media having a lateral exchange control layer formed on a magnetic oxide layer of a magnetic recording layer. A cap layer is formed over the lateral exchange control layer. The lateral exchange control layer can be an alloy comprising Co and one or more of W, Ru, Hf, Ta, Nb and Fe. The lateral exchange control layer has the highest magnetic saturation moment among all the recording layers, and increases spacing between magnetic grains (e.g. increased non-magnetic boundary width), thereby reducing lateral exchange sigma. The presence of lateral exchange control increases signal to noise ratio and reduces bit error rate and increases areal density.
1. A magnetic media, comprising:
a magnetically soft under-layer; and
a magnetic recording layer formed over the magnetically soft under-layer, the magnetic recording layer further comprising:
a granular magnetic layer;
a magnetic lateral exchange control layer positioned on the granular magnetic layer; and
a magnetic cap layer formed over the lateral exchange control layer, wherein the magnetic cap layer comprises magnetic grains separated by non-magnetic grain boundaries, and wherein the non-magnetic grain boundaries have a thickness that gradually decreases with increasing distance from the lateral exchange control layer;
wherein the lateral exchange control layer comprises an alloy that includes Co and at least one of W, Ru, Hf, Ta, Nb and Fe, and wherein the lateral exchange control layer is formed as islands on the granular magnetic layer.
2. The magnetic media as in claim 1 , wherein the concentration of non-magnetic material in the lateral exchange control layer is less than 25 atomic percent.
3. The magnetic media as in claim 1 , wherein the concentration of non-magnetic material in the lateral exchange control layer is greater than 10 atomic percent and less than 25 atomic percent.
4. The magnetic media as in claim 1 , wherein the concentration of one or more of W, Ru, Hf, Ta, Nb and Fe is at least 10 atomic percent.
5. The magnetic media as in claim 1 wherein the lateral exchange control layer has a higher magnetic saturation than the granular magnetic layer or the cap layer.
6. The magnetic media as in claim 1 wherein the lateral exchange control layer has a magnetic saturation of between 650 emu/cc and 800 emu/cc.
7. The magnetic media as in claim 1 , wherein the lateral exchange control layer contains no oxide.
8. The magnetic media as in claim 1 , wherein the lateral exchange control layer has a thickness of 0.1 nm to 0.5 nm.
9. The magnetic media as in claim 1 wherein the cap layer is at least 1.0 nm thick and wherein the non-magnetic grain boundaries have a width of at least 0.5 nm at a location 1.0 nm from the lateral exchange control layer.
10. The magnetic media as in claim 1 , wherein the lateral exchange control layer is formed as islands separated by non-magnetic boundary layers, and wherein the boundary layers at the location of the lateral exchange control layer have a width of at least 1 nm.
11. A magnetic media, comprising:
a magnetic recording layer formed as a plurality of magnetic structures separated by non-magnetic boundary layers extending vertically between the magnetic structures, the magnetic structures comprising;
a magnetic oxide structure;
a magnetic lateral exchange control layer having a surface energy higher than that of Co causing it to be formed as an island on the magnetic oxide structure; and
a magnetic cap layer formed over the magnetic oxide structure, wherein the magnetic cap layer comprises magnetic grains separated by non-magnetic grain boundaries, and wherein the non-magnetic grain boundaries have a thickness that gradually decreases with increasing distance from the lateral exchange control layer.
12. The magnetic media as in claim 11 , wherein the lateral exchange control layer is an alloy comprising Co and at least one of W, Ru, Hf, Ta, Nb and Fe.
13. The magnetic media as in claim 11 , wherein the lateral exchange control layer has a higher magnetic saturation than the magnetic oxide structure or the magnetic cap layer.
14. The magnetic media as in claim 11 , wherein the lateral exchange control layer has a magnetic saturation of between 650 emu/cc and 800 emu/cc.
15. The magnetic media as in claim 11 , wherein the non-magnetic boundary layers have a width of at least 1 nm at the location of the lateral exchange control layer.
16. The magnetic media as in claim 11 , wherein the non-magnetic boundary layers have a width of at least 0.5 nm at a location within the cap layer that is 1.0 nm above the lateral exchange control layer.
17. A magnetic data recording system, comprising:
a housing;
a magnetic media mounted within the housing; and
a magnetic read write transducer mounted within the housing for movement adjacent to a surface of the magnetic media;
wherein the magnetic media comprises:
a magnetically soft under-layer;
a magnetic recording layer formed over the magnetically soft under-layer, the magnetic recording layer further comprising:
a granular magnetic layer;
a magnetic lateral exchange control layer positioned on the granular magnetic layer; and
a magnetic cap layer formed over the lateral exchange control layer wherein the magnetic cap layer comprises magnetic grains separated by non-magnetic grain boundaries, wherein the non-magnetic grain boundaries have a thickness that gradually decreases with increasing distance from the lateral exchange control layer;
wherein the lateral exchange control layer comprises an alloy that includes Co and at least one of W, Ru, Hf, Ta, Nb and Fe, and wherein the lateral exchange control layer is formed as islands on the granular magnetic layer.