Magnetic recording medium and the method of manufacturing the same

Abstract

A method of manufacturing a magnetic recording media includes a magnetic recording layer of a granular magnetic layer that has ferromagnetic crystal grains and an oxide nonmagnetic grain boundary or a nitride nonmagnetic grain boundary surrounding the ferromagnetic crystal grains. It further has an overcoating layer on the granular magnetic recording layer. The overcoating layer contains a nonmagnetic metal or a nonmagnetic alloy that can be diffused into the nonmagnetic grain boundary. The atoms coated on the granular magnetic recording layer diffuse into the nonmagnetic grain boundary even without being annealed, and promote to isolate the ferromagnetic crystal grains from each other. The overcoating can be removed after its formation to reduce the magnetic gap between the magnetic recording layer and the magnetic recording head.

What is claimed is:  
     
         1 . A magnetic recording medium comprising: 
 a nonmagnetic substrate;    an underlayer above the nonmagnetic substrate;    a magnetic recording layer on the underlayer; and    an overcoating layer on the magnetic recording layer,    wherein the magnetic recording layer comprises a granular magnetic layer comprising ferromagnetic crystal grains and a nonmagnetic grain boundary comprising an oxide or a nitride surrounding the ferromagnetic crystal grains, and    wherein the overcoating layer comprises a nonmagnetic metal or a nonmagnetic alloy adapted to be diffused into the nonmagnetic grain boundary.    
     
     
         2 . The magnetic recording medium according to  claim 1 , wherein the nonmagnetic metal or nonmagnetic alloy is composed of an element selected from the group consisting of Sc, Ti, V, Cr, Mn, Cu, Zn, Al, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Si, Sb, Hf, Ta, W, Re, Os, Ir, Pt, and Au.  
     
     
         3 . A method of manufacturing a magnetic recording medium, comprising the steps of: 
 forming an underlayer above a nonmagnetic substrate;    forming a magnetic recording layer on the underlayer; and    forming an overcoating layer on the magnetic recording layer,    wherein the magnetic recording layer comprises a granular magnetic layer comprising ferromagnetic crystal grains and a nonmagnetic grain boundary comprising an oxide or a nitride surrounding the ferromagnetic crystal grains, and    wherein the overcoating layer comprises a nonmagnetic metal or a nonmagnetic alloy adapted to be diffused into the nonmagnetic grain boundary.    
     
     
         4 . The method according to  claim 3 , further comprising the step of removing the overcoating layer after diffusing the nonmagnetic metal or the nonmagnetic alloy into the nonmagnetic grain boundary.  
     
     
         5 . The magnetic recording medium according to  claim 3 , wherein the nonmagnetic metal or the nonmagnetic alloy is composed of an element selected from the group consisting of Sc, Ti, V, Cr, Mn, Cu, Zn, Al, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Hf, Ta, W, Re, Os, Ir, Pt, and Au.  
     
     
         6 . The magnetic recording medium according to  claim 4 , wherein the nonmagnetic metal or the nonmagnetic alloy is composed of an element selected from the group consisting of Sc, Ti, V, Cr, Mn, Cu, Zn, Al, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Hf, Ta, W, Re, Os, Ir, Pt, and Au.  
     
     
         7 . A magnetic recording medium formed by the method according to  claim 3 .  
     
     
         8 . A magnetic recording medium formed by the method according to  claim 4 .  
     
     
         9 . A magnetic recording medium formed by the method according to  claim 5 .  
     
     
         10 . A magnetic recording medium formed by the method according to  claim 6.