Magnetic recording medium, method for manufacturing same, and film-forming apparatus

Abstract

A magnetic recording medium including a base material which has flexibility, and a laminated film, in which a variation in magnetic characteristics is within ±10% over a division of 300 m in a longitudinal direction of the base material.

The invention is claimed as follows: 
     
         1 . A magnetic recording medium comprising:
 a base material which has flexibility; and   a laminated film,   wherein a variation in magnetic characteristics is within ±10% over a division of 300 m in a longitudinal direction of the base material.   
     
     
         2 . The magnetic recording medium according to  claim 1 ,
 wherein the laminated film includes a lower coating layer and a perpendicular recording layer.   
     
     
         3 . The magnetic recording medium according to  claim 2 ,
 wherein the lower coating layer includes Ti and Cr, and   the perpendicular recording layer has a granular structure where particles which include Co, Pt, and Cr are separated by an oxide.   
     
     
         4 . The magnetic recording medium according to  claim 2 ,
 wherein the lower coating layer has an amorphous state.   
     
     
         5 . The magnetic recording medium according to  claim 2 ,
 wherein the laminated film further includes an intermediate layer.   
     
     
         6 . The magnetic recording medium according to  claim 5 ,
 wherein the intermediate layer includes Ru or NiW.   
     
     
         7 . The magnetic recording medium according to  claim 2 ,
 wherein the laminated film further includes at least one type of layer out of a soft magnetic layer and a CAP layer.   
     
     
         8 . The magnetic recording medium according to  claim 1 ,
 wherein a variation in magnetic characteristics is within ±5% over a division of 300 m or more in the longitudinal direction of the base material.   
     
     
         9 . The magnetic recording medium according to  claim 1 ,
 wherein the magnetic characteristics are a holding power Hc, a squareness ratio Rs, and an orientation strength Δθ 50 .   
     
     
         10 . The magnetic recording medium according to  claim 1 ,
 wherein the laminated film is film-formed by a physical deposition method.   
     
     
         11 . The magnetic recording medium according to  claim 10 ,
 wherein the physical deposition method is a sputtering method.   
     
     
         12 . A film-forming apparatus comprising:
 a rotating body which moves a base material with a strip shape which has flexibility;   a plurality of cathodes which are provided to oppose a rotating surface of the rotating body; and   a plurality of accommodating sections which accommodate each of the plurality of cathodes.   
     
     
         13 . The film-forming apparatus according to  claim 12 ,
 wherein the plurality of accommodating sections are configured so as to be able to exhaust a vacuum and to carry out heating and cooling.   
     
     
         14 . A method for manufacturing a magnetic recording medium comprising:
 sequentially film-forming a plurality of thin films on a base material using a plurality of cathodes which are provided on a moving path of the base material while moving the base material with a strip shape which has flexibility,   wherein each of the plurality of cathodes is accommodated in a plurality of accommodating sections.   
     
     
         15 . The method for manufacturing a magnetic recording medium according to  claim 14 , further comprising:
 heating the plurality of accommodating sections before film-forming the plurality of thin films.   
     
     
         16 . The method for manufacturing a magnetic recording medium according to  claim 15 ,
 wherein a temperature of inner walls of the plurality of accommodating sections is held at 200° C. or higher for 30 minutes or longer by the heating.   
     
     
         17 . The method for manufacturing a magnetic recording medium according to  claim 14  further comprising:
 cooling the plurality of accommodating sections while film-forming the plurality of thin films. 
 
     
     
         18 . The method for manufacturing a magnetic recording medium according to  claim 17 ,
 wherein the temperature of inner walls of the plurality of accommodating sections is held at 90° C. or lower by the cooling.