Method for manufacturing magnetic recording medium
View Patent ↗A method for manufacturing a magnetic recording medium includes the steps of (a) forming a perpendicular magnetic recording layer and (b) applying an ion beam to regions between tracks of the perpendicular magnetic recording layer so as to form separation regions for magnetically separating the tracks from each other. In the step (a), a continuous film layer composed of a multilayer film is formed, and CoB layers and Pd layers are laminated in the multilayer film. In the step (b), the CoB layers and the Pd layers are melted by the ion beam so as to form an alloy of metals contained in the CoB layers and the Pd layers to thereby form the separation regions.
1. A method for manufacturing a magnetic recording medium comprising the steps of:
(a) forming a magnetic recording layer comprising a first magnetic layer and a second magnetic layer, the first magnetic layer being a granular layer having a granular structure while the second magnetic layer being a continuous film layer, wherein the continuous film layer is a multilayer film,
(b) applying an ion beam to regions between tracks of the magnetic recording medium so as to form separation regions for magnetically separating the tracks from each other, wherein:
the step (b) is performed after the step (a),
the step (a) comprises the step of forming the second magnetic layer on the first magnetic layer, and a plurality of types of metal films having different compositions are laminated in the multilayer film; and
in the step (b), the second magnetic layer is irradiated with the ion beam such that the plurality of types of metal films are melted by the ion beam to form an alloy of metals contained in the plurality of types of metal films to thereby form the separation regions, and the separation regions are formed only in the second magnetic layer of the magnetic recording layer of the magnetic recording medium,
wherein the resulting separation regions formed in the second magnetic layer are nonmagnetic.
2. The method for manufacturing a magnetic recording medium according to claim 1 ,
wherein the first magnetic layer and the second magnetic layer are exchange-coupled to each other.
3. The method for manufacturing a magnetic recording medium according to claim 2 ,
wherein the magnetic recording medium is used for perpendicular magnetic recording,
the first magnetic layer has magnetic crystal grains exhibiting perpendicular magnetic anisotropy and nonmagnetic substances for magnetically separating the magnetic crystal grains from each other at grain boundaries of the magnetic crystal grains, and
the second magnetic layer has magnetic grains exchange-coupled to the magnetic crystal grains, a grain boundary width of the magnetic grains being smaller than a grain boundary width of the magnetic crystal grains.
4. The method for manufacturing a magnetic recording medium according to claim 2 ,
wherein the magnetic recording medium is used for perpendicular magnetic recording and comprises a substrate for disposing the first magnetic layer and the second magnetic layer,
the first magnetic layer has magnetic crystal grains exhibiting perpendicular magnetic anisotropy and nonmagnetic substances for magnetically separating the magnetic crystal grains from each other at grain boundaries of the magnetic crystal grains, and
the second magnetic layer has magnetic grains exchange-coupled to the magnetic crystal grains and exchange-coupled to each other with a strength larger than a bonding strength between the magnetic crystal grains in the first magnetic layer in a direction parallel to a main surface of the substrate.
5. The method for manufacturing a magnetic recording medium according to claim 1 ,
a recording region that is applied with the ion beam has a first saturation magnetic field,
a recording region that is not applied with the ion beam has a second saturation magnetic field, and
the first saturation magnetic field is greater than the second saturation magnetic field.
6. The method for manufacturing a magnetic recording medium according to claim 1 , wherein the plurality of types of metal films comprise of CoCr layers or CoB layers alternately laminated with Pd layers or Pt layers.