Perpendicular magnetic recording medium and method for manufacturing the same
Provided are a perpendicular magnetic recording medium and a method for manufacturing the same, the perpendicular magnetic recording medium including an alloy (FePt, FePd, or CoPt) having a large K u value with an L1 0 type ordered structure, and obtained with achievement of controlled crystal orientation and thin film formation without heating. Specifically, in the perpendicular magnetic recording medium, at least a nonmagnetic seed layer, a nonmagnetic underlayer, and a magnetic layer are formed in this order on a nonmagnetic substrate. The nonmagnetic seed layer includes a MgO layer and a metal layer having a body-centered cubic (bcc) structure. The nonmagnetic underlayer has a NaCl type structure of one selected from the group consisting of MgO, NiO, TiO, CrN, Ti carbides, and Ti nitrides. The magnetic layer includes an alloy selected from the group consisting of FePt, FePd, and CoPt having an L1 0 type ordered structure.
1. A perpendicular magnetic recording medium comprising:
a nonmagnetic seed layer, a nonmagnetic underlayer, and a magnetic layer formed in this order on a nonmagnetic substrate,
wherein the nonmagnetic seed layer includes a MgO layer in direct contact with a metal layer thereon having a body-centered cubic (bcc) structure,
the nonmagnetic underlayer has a NaCl type structure of one selected from the group consisting of MgO, NiO, TiO, CrN, Ti carbides, and Ti nitrides, the nonmagnetic underlayer being disposed directly on the nonmagnetic seed layer, and
the magnetic layer includes an alloy selected from the group consisting of FePt, FePd, and CoPt having an L1 0 type ordered structure.
2. The perpendicular magnetic recording medium according to claim 1 , wherein all of a (001) crystal lattice plane of the metal layer, a (001) crystal lattice plane of the NaCl type structure in the nonmagnetic underlayer, and a (001) crystal lattice plane of the L1 0 type ordered structure in the magnetic layer are parallel to a film surface.
3. The perpendicular magnetic recording medium according to claim 1 , wherein a surface energy difference between a (002) plane and a (110) plane of the metal layer is 300 erg/cm 2 or smaller.
4. The perpendicular magnetic recording medium according to claim 1 , wherein the metal layer has a thickness of 1 nm to 50 nm both inclusive.
5. The perpendicular magnetic recording medium according to claim 1 , wherein the MgO layer disposed under the metal layer has a thickness equal to or larger than 0.2 nm and less than or equal to 3 nm.
6. A method for manufacturing a perpendicular magnetic recording medium, comprising:
a step of forming at least a nonmagnetic seed layer, a nonmagnetic underlayer, and a magnetic layer in this order on a nonmagnetic substrate,
wherein the nonmagnetic seed layer includes a MgO layer in direct contact with a metal layer thereon having a body-centered cubic (bcc) structure,
the nonmagnetic underlayer has a NaCl type structure of one selected from the group consisting of MgO, NiO, TiO, CrN, Ti carbides, and Ti nitrides, the nonmagnetic underlayer being disposed directly on the nonmagnetic seed layer,
the magnetic layer includes an alloy selected from the group consisting of FePt, FePd, and CoPt having an L1 0 type ordered structure, and
in the formation of the magnetic layer, the nonmagnetic substrate has a substrate temperature of 200° C. to 350° C., and a process gas has an impurity concentration of less than or equal to 5 ppb.