Perpendicular magnetic recording medium
View Patent ↗A perpendicular type of magnetic recording medium includes a substrate, a soft magnetic underlying section including a plurality of distinct layers soft magnetic material, a recording section, and an intermediate section upon which the recording section is formed. The intermediate section is provided to improve the crystal orientation and impart a desired magnetic characteristic to the recording section. An uppermost one of the layers of soft magnetic material which, of all of the layers of soft magnetic material, is disposed closest to the intermediate section is predisposed to induce the intermediate section to crystallize in a desired way as it is formed. Therefore, the intermediate section may have a minimal thickness and yet achieve a crystallization that is sufficient to control the forming of the recording section.
1. A perpendicular magnetic recording medium comprising:
a substrate;
a soft magnetic material section disposed on the substrate, the soft magnetic material section comprising a plurality of distinct layers each of soft magnetic material;
an intermediate section comprising crystalline material disposed on the soft magnetic material section; and
a recording section comprising a crystalline layer of magnetic material disposed on the intermediate section,
wherein the intermediate section comprises a layer of material predisposed to control a crystallizing of the material of the recording section when the recording section is formed on the intermediate section, and
of the plurality of layers of soft magnetic material, an uppermost one of the layers closest to the intermediate section is predisposed to impart a desired crystalline structure to material of the intermediate section when the intermediate section is formed on the soft magnetic material section,
wherein the soft magnetic material section includes of a lowermost layer of soft magnetic material and an uppermost portion comprising at least one unit layer of soft magnetic material,
of all of the layers of soft magnetic material of the medium, the lowermost layer of soft magnetic material is disposed closest to the substrate, and
the lowermost layer of soft magnetic material generates an anisotropic magnetic field that is weaker than that generated by the uppermost portion of the soft magnetic material section, and
wherein the uppermost portion of the soft magnetic material section comprises:
a plurality of unit layers each of soft magnetic material, and
spacers interposed between adjacent ones of the unit layers of soft magnetic layer material, and
adjacent ones of the unit layers of soft magnetic material have a Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling structure, whereby the adjacent ones of the unit layers are magnetically coupled.
2. The perpendicular magnetic recording medium of claim 1 , wherein the uppermost layer of soft magnetic material has a same crystalline structure as the intermediate section.
3. The perpendicular magnetic recording medium of claim 1 , wherein the uppermost layer of soft magnetic material has an FCC crystalline structure or an HCP crystalline structure.
4. The perpendicular magnetic recording medium of claim 1 , wherein the soft magnetic material section further comprises a separation layer of non-magnetic material interposed between the lowermost layer of soft magnetic material and the uppermost portion of the soft magnetic material section.
5. The perpendicular magnetic recording medium of claim 1 , wherein the unit layers of soft magnetic material each have a crystalline structure and include the uppermost unit layer of soft magnetic material which, of all of said unit layers, is disposed under and closest to the intermediate section,
the spacers include an uppermost spacer which, of all of said spacers, is disposed under and closest to the uppermost layer of soft magnetic material, and
the uppermost spacer is predisposed to orient unit crystal structures of the uppermost unit layer of soft magnetic material when the uppermost unit layer is formed on the uppermost spacer.
6. The perpendicular magnetic recording medium of claim 5 , wherein the uppermost spacer comprises a layer of material selected from the group consisting of Ru, MgO, and Ni.
7. The perpendicular magnetic recording medium of claim 1 , wherein the intermediate section comprises a layer of material selected from the group consisting of Ru, MgO, and Ni.
8. The perpendicular magnetic recording medium of claim 1 , wherein the intermediate section comprises a layer of Ru and a layer of an Ru oxide.
9. The perpendicular magnetic recording medium of claim 1 , wherein the thickness of the intermediate section is in a range of 8 nm to 16 nm.
10. The perpendicular magnetic recording medium of claim 9 , wherein the intermediate section consists of at least one layer of material comprising Ru.
11. The perpendicular magnetic recording medium of claim 10 , wherein the intermediate section consists of a lower layer of Ru, and an upper layer of an Ru oxide.
12. A perpendicular magnetic recording medium comprising:
a substrate;
a soft magnetic material section disposed on the substrate, the soft magnetic material section comprising a plurality of distinct layers each of soft magnetic material;
an intermediate section comprising crystalline material disposed on the soft magnetic material section; and
a recording section comprising a crystalline layer of magnetic material disposed on the intermediate section,
wherein the intermediate section comprises a layer of material predisposed to control a crystallizing of the material of the recording section when the recording section is formed on the intermediate section, and
of the plurality of layers of soft magnetic material, an uppermost one of the layers closest to the intermediate section is predisposed to impart a desired crystalline structure to material of the intermediate section when the intermediate section is formed on the soft magnetic material section,
wherein the distinct layers of soft magnetic material consist of a lowermost layer of soft magnetic material and an uppermost layer of soft magnetic material,
the lowermost layer of soft magnetic material is disposed closest to the substrate, and the uppermost layer of soft magnetic material is disposed closest to the intermediate section,
the lowermost layer of soft magnetic material generates an anisotropic magnetic field that is weaker than that generated by the uppermost layer of soft magnetic material, and
wherein the lowermost layer of soft magnetic material is thicker and of the same material as the uppermost layer of soft magnetic material.