Magnetic recording medium, process for producing same, and magnetic recording reproducing apparatus
View Patent ↗A magnetic recording medium is provided, which has at least one soft magnetic layer, at least one seed layer, at least one underlayer and at least one perpendicular magnetic recording layer, and is characterized in that the or each seed layer is comprised of a covalently bonded material. The covalently bonded material preferably predominantly comprises a nitride having a hexagonal crystal structure, more preferably, predominantly comprises aluminum nitride having a hexagonal wurtzite crystal structure. This magnetic recording medium is superior in recording and reproducing an information with high density.
1. A magnetic recording medium having at least one soft magnetic layer, at least one seed layer, at least one underlayer and at least one perpendicular magnetic recording layer having a (002) crystal plane-orientated hcp structure, which are formed in turn on a non-magnetic substrate, wherein:
at least one of said at least one seed layer is comprised of a covalently bonded material predominantly comprising a nitride having a hexagonal crystal structure;
said at least one underlayer is comprised of Ru or Re, or an alloy thereof, which has a (002) crystal plane-orientated hcp structure, or Pt or Pd, or an alloy thereof, which has a (111) crystal plane-orientated (fcc) structure; and
a layer comprised of a material selected from the group consisting of Ni—Ta, Ni—V, Ni—Nb, Ni—W, Ni—Fe and Ni—Mn and having a fcc structure is further formed between said at least one soft magnetic layer and said at least one seed layer.
2. The magnetic recording medium according to claim 1 , wherein said covalently bonded material predominantly comprises aluminum nitride (AlN) having a hexagonal wurtzite crystal structure.
3. The magnetic recording medium according to claim 1 , wherein said covalently bonded material has an average crystal grain diameter in the range of 3 nm to 12 nm.
4. The magnetic recording medium according to claim 1 , wherein said at least one seed layer has a total thickness in the range of 0.1 nm to 40 nm.
5. The magnetic recording medium according to claim 1 , wherein said at least one soft magnetic layer has a soft magnetic amorphous structure.
6. The magnetic recording medium according to claim 1 , wherein said at least one perpendicular magnetic recording layer is comprised of an oxide magnetic material.
7. A process for producing a magnetic recording medium, which comprises forming at least one soft magnetic layer, at least one seed layer, at least one underlayer and at least one perpendicular magnetic recording layer having a (002) crystal plane-orientated hcp structure, in turn on a non-magnetic substrate, wherein:
said at least one seed layer is formed from a covalently bonded material predominantly comprising a nitride having a hexagonal crystal structure;
said at least one underlayer is comprised of Ru or Re, or an alloy thereof, which has a (002) crystal plane-orientated hcp structure, or Pt or Pd, or an alloy thereof, which has a (111) crystal plane-orientated (fcc) structure; and
a layer comprised of a material selected from the group consisting of Ni—Ta, Ni—V, Ni—Nb, Ni—W, Ni—Fe and Ni—Mn and having a fcc structure is further formed between said at least one soft magnetic layer and said at least one seed layer.
8. The process for producing a magnetic recording medium according to claim 7 , wherein the formation of the seed layer is carried out by forming the covalently bonded material into a thin film on a heated substrate.
9. The process for producing a magnetic recording medium according to claim 7 , wherein the covalently bonded material predominantly comprises aluminum nitride (AlN) having a hexagonal wurtzite crystal structure.
10. The process for producing a magnetic recording medium according to claim 7 , wherein the covalently bonded material has an average crystal grain diameter in the range of 3 nm to 12 nm.
11. The process for producing a magnetic recording medium according to claim 7 , wherein said at least one seed layer has a total thickness in the range of 0.1 nm to 40 nm.
12. The process for producing a magnetic recording medium according to claim 7 , wherein said at least one soft magnetic layer has a soft magnetic amorphous structure.
13. The process for producing a magnetic recording medium according to claim 7 , wherein said at least one perpendicular magnetic recording layer is formed from an oxide magnetic material.
14. A magnetic recording reproducing apparatus provided with a magnetic recording medium and a magnetic head for recording and reproducing an information in the magnetic recording medium, characterized in that the magnetic recording medium is a magnetic recording medium as claimed in claim 1 .