Magnetic recording medium and manufacturing method thereof

Abstract

A high-density magnetic recording medium uses a nonmetallic substrate, while still providing high in-plane magnetic anisotropy and remanent coercivity. Such a medium can be formed by depositing a seed layer on a textured surface of the nonmetallic substrate in a gas mixture containing oxygen or nitrogen and an inert gas, while controlling the oxygen concentration or nitrogen concentration, and subsequently exposing the surface of the seed layer to oxygen or nitrogen.

1 - 10 . (canceled)  
     
     
         11 . The magnetic recording medium according to  claim 18 , wherein: 
 the surface of the seed layer is exposed to gas containing at least one of oxygen or nitrogen, and    the seed layer is composed of Ni—P, which is deposited on the nonmetallic substrate in a gas mixture containing oxygen and an inert gas, the concentration of oxygen being 0.15 to 0.55 vol %.    
     
     
         12 . The magnetic recording medium according to  claim 11 , wherein the oxygen concentration in the gas mixture, when depositing the seed layer, is 0.20 to 0.45 vol %.  
     
     
         13 . The magnetic recording medium, according to  claim 18 , wherein: 
 the surface of the seed layer is exposed to gas containing at least one of oxygen or nitrogen: and    the seed layer is composed of W—Nb, which is deposited on the nonmetallic substrate in a gas mixture containing nitrogen and other inert gas, the concentration of nitrogen being 1.8 to 3.6 vol %.    
     
     
         14 . The magnetic recording medium according to  claim 13 , wherein the nitrogen concentration in the gas mixture, when depositing the seed layer, is 1.8 to 2.7 vol %.  
     
     
         15 . The magnetic recording medium according to  claim 18 , wherein: 
 the surface of the seed layer is exposed to gas containing at least one of oxygen or nitrogen: and    the seed layer is composed of Ni—Nb, which is deposited on the nonmetallic substrate in a gas mixture containing nitrogen and other inert gas the concentration of nitrogen being 0.4 to 3.6 vol %.    
     
     
         16 . The magnetic recording medium according to  claim 15 , wherein the nitrogen concentration in the gas mixture, when depositing the seed layer, is 0.4 to 0.9 vol %.  
     
     
         17 . The magnetic recording medium according to  claim 11 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.50, and a remanent coercivity of at least 3500 Oe.  
     
     
         18 . A magnetic recording medium comprising: 
 a nonmetallic substrate having a textured surface;    a seed layer composed of one of Ni—P, Ni—Nb, or W—Nb formed on the substrate;    a nonmagnetic underlayer formed on the seed layer; and    a magnetic layer formed on the substrate,    wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.30, and a remanent coercivity of at least 2800 Oe.    
     
     
         19 . The magnetic recording medium according to  claim 18 , wherein the seed layer is composed of Ni—P and the recording medium has an in-plane magnetic anisotropy of at least 1.50, and a remanent coercivity of at least 3500 Oe.  
     
     
         20 . The magnetic recording medium according to  claim 19 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.60, and a remanent coercivity of at least 3700 Oe.  
     
     
         21 . The magnetic recording medium according to  claim 18 , wherein the seed layer is composed of W—Nb.  
     
     
         22 . The magnetic recording medium according to  claim 21 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.40, and a remanent coercivity of at least 3500 Oe.  
     
     
         23 . The magnetic recording medium according to  claim 18 , wherein the seed layer is composed of Ni—Nb and the recording medium has an in-plane magnetic anisotropy of at least 1.40, and a remanent coercivity of at least 3200 Oe.  
     
     
         24 . The magnetic recording medium according to  claim 23 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.45, and a remanent coercivity of at least 3600 Oe.  
     
     
         25 . The magnetic recording medium according to  claim 13 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.40, and a remanent coercivity of at least 3500 Oe.  
     
     
         26 . The magnetic recording medium according to  claim 15 , wherein the magnetic recording medium has an in-plane magnetic anisotropy of at least 1.40, and a remanent coercivity of at least 3200 Oe.