Magnetic recording medium and manufacturing method thereof

Abstract

A magnetic recording medium includes a first underlying film of a NiTa alloy having a nonmagnetic amorphous structure and formed on a nonmagnetic substrate, and a second underlying film made of an alloy containing Cr and Ti, further a first magnetic film of a CoCrPt alloy, a nonmagnetic intermediate film of Ru and a second magnetic film of a CoCrPtB alloy that are serially formed over the first underlying film, wherein oxygen locally exists in an interface between the first underlying film and the second underlying film.

What is claimed is:  
     
         1 . A magnetic recording medium including a first underlying film formed on a nonmagnetic substrate and containing a NiTa alloy having a nonmagnetic amorphous structure, and a second underlying film using an alloy containing at least Cr and Ti, further a first magnetic film using a CoCrPt alloy, a nonmagnetic intermediate film containing Ru and a second magnetic film using a CoCrPtB alloy that are serially formed over said first underlying layer, wherein oxygen exists in an interface between said first underlying film and said second underlying film.  
     
     
         2 . A magnetic recording medium according to  claim 1 , wherein said oxygen is locally dispersed in said interface.  
     
     
         3 . A magnetic recording medium according to  claim 1 , wherein a Ti concentration of said second underlying film is 10 at % to 15 at %, and a Pt concentration of the CoCrPt alloy as said first magnetic film is 3 at % to 8 at %.  
     
     
         4 . A magnetic recording medium according to  claim 1 , wherein a film thickness of said second underlying film is 5 nm to 15 nm, and a half value width of a locking curve in a (11.0) diffraction peak appearing at an overlapping position of said first and second magnetic films is equal to or less than 80.  
     
     
         5 . A method of manufacturing a magnetic recording medium, comprising the steps of: 
 forming a first underlying film formed of a NiTa alloy having a nonmagnetic amorphous structure on a nonmagnetic substrate;    exposing said first underlying film to an oxygen atmosphere wherein a product of an oxygen partial pressure and an exposure time to said oxygen atmosphere from said step of forming said first underlying film to a step of forming a second underlying film is 15 (mPa·sec) to 35 (mPa·sec);    forming said second underlying film formed of an alloy containing at least Cr and Ti on said first underlying film, wherein a Ti concentration of said second underlying film is 10 at % to  15  at %; and    forming serially a first magnetic film formed of a CoCrPt alloy having a Pt concentration of 3 at % to 8 at %, a nonmagnetic intermediate film containing Ru and a second magnetic film formed of a CoCrPtB alloy, over said second underlying film.    
     
     
         6 . A method of manufacturing a magnetic recording medium, comprising the steps of: 
 forming a first underlying film formed of a NiTa alloy having a nonmagnetic amorphous structure on a nonmagnetic substrate;    exposing said first underlying film to an oxygen atmosphere wherein a product of an oxygen pressure and an exposure time to said oxygen atmosphere from said step of forming said first underlying film to a step of forming a second underlying film is 20 (mPa·sec) to 40 (mPa·sec);    forming said second underlying film formed of an alloy containing at least Cr, Ti and B on said first underlying film, wherein a Ti concentration of said second underlying film is 10 at % to 15 at %; and    forming serially a first magnetic film formed of a CoCrPt alloy having a Pt concentration of 3 at % to 8 at %, a nonmagnetic intermediate film containing Ru and a second magnetic film formed of a CoCrPtB alloy, over said second underlying film.