Magnetic recording medium

Abstract

A magnetic recording medium includes a flexible substrate, an amorphous seed layer, an under layer containing Ru, and a recording layer having a granular structure. The seed layer is provided between the substrate and the under layer. The under layer has a thickness in a range of 5 to 50 nm.

What is claimed is: 
     
         1 . A magnetic recording medium comprising:
 a flexible substrate;   an amorphous seed layer;   an under layer containing Ru; and   a recording layer having a granular structure,   wherein the seed layer is provided between the substrate and the under layer, and   the under layer has a thickness in a range of 5 to 50 nm.   
     
     
         2 . The magnetic recording medium according to  claim 1 ,
 wherein the seed layer includes an alloy containing Ti and Cr.   
     
     
         3 . The magnetic recording medium according to  claim 1 ,
 wherein the seed layer reduces surface irregularities of the substrate.   
     
     
         4 . The magnetic recording medium according to  claim 1 ,
 wherein the substrate has a Young's modulus in a range of 6,250 to 16,000 N/mm 2 .   
     
     
         5 . The magnetic recording medium according to  claim 1 ,
 wherein the substrate has a Young's modulus in a range of 6,250 to 7,000 N/mm 2 .   
     
     
         6 . The magnetic recording medium according to  claim 1 ,
 wherein the substrate has a thickness of 10.0 μm or less.   
     
     
         7 . The magnetic recording medium according to  claim 1 ,
 wherein the magnetic recording medium has a crack-resistant load in a range of 200 to 500 [g/12.75 mm].   
     
     
         8 . The magnetic recording medium according to  claim 1 ,
 wherein the recording layer has a granular structure in which grains containing Co, Pt, and Cr are separated by oxides.   
     
     
         9 . The magnetic recording medium according to  claim 8 ,
 wherein the recording layer has an average composition represented by the following formula (1):
   (CO x Pt y Cr 100-x-y ) 100-z —(SiO 2 ) z   (1)
 
   wherein, in the formula (1), x, y, and z satisfy 69≦x≦72, 12≦y≦16, 9≦z≦12, respectively.