Perpendicular magnetic recording medium and magnetic recording apparatus

Abstract

A soft magnetic laminate layer is arranged between a nonmagnetic substrate and a perpendicular magnetic recording layer so as to provide a perpendicular magnetic recording medium low in noise and capable of a high density recording. The soft magnetic laminate layer comprises a soft magnetic layer having a thickness not larger than 500 Å and a nonmagnetic layer, comprises a first soft magnetic layer and a second soft magnetic layer differing from the first soft magnetic layer in the crystal structure, or comprises a layer of a granular structure consisting of magnetic particles and a nonmagnetic matrix and a soft magnetic layer.

What is claimed is:  
     
         1 . A magnetic recording medium comprising: 
 a nonmagnetic substrate;    a perpendicular magnetic recording layer for recording signal; and    a soft magnetic laminate layer formed between said nonmagnetic substrate and said perpendicular magnetic recording layer for recording signal, and including a soft magnetic layer which has a thickness not larger than 500 Å and a nonmagnetic layer.    
     
     
         2 . The magnetic recording medium according to  claim 1 , wherein the thickness of said nonmagnetic layer is not larger than 1.5 times the thickness of said soft magnetic layer.  
     
     
         3 . The magnetic recording medium according to  claim 1 , wherein the value of the saturation magnetization per layer of said soft magnetic layer is not larger than 90% of the saturation magnetization value under a bulk state.  
     
     
         4 . The magnetic recording medium according to  claim 1 , wherein said soft magnetic layer contains as a main component at least one element selected from the group consisting of Fe, Co and Ni.  
     
     
         5 . The magnetic recording medium according to  claim 1 , wherein said nonmagnetic layer is formed of at least one element selected from the group consisting of B, C, Ti, Si, Al, Cr, Ru, Zr, Nb, and Ta.  
     
     
         6 . The magnetic recording medium according to  claim 1 , wherein said soft magnetic layer is formed of an Fe—Al—Si alloy layer.  
     
     
         7 . The magnetic recording medium according to  claim 1 , wherein said perpendicular magnetic recording layer is formed of at least one layer of a Co—Pt—Cr—O mainly containing magnetic thin film.  
     
     
         8 . A magnetic recording medium comprising: 
 a nonmagnetic substrate;    a perpendicular magnetic recording layer;    a soft magnetic laminate layer formed between the nonmagnetic substrate and the perpendicular magnetic medium, and including a first soft magnetic layer, and a second soft magnetic layer laminated on said first soft magnetic layer and differing from said first soft magnetic layer in the crystal structure.    
     
     
         9 . The magnetic recording medium according to  claim 8 , wherein each of said first and second soft magnetic layers contains as a main component at least one element selected from the group consisting of Fe, Co and Ni.  
     
     
         10 . A magnetic recording medium comprising: 
 a nonmagnetic substrate;    a perpendicular magnetic recording layer;    a soft magnetic laminate layer formed between the nonmagnetic substrate and the perpendicular magnetic medium, and including a soft magnetic granular layer formed of a nonmagnetic matrix and soft magnetic metal particles dispersed in said matrix, and a soft magnetic layer.    
     
     
         11 . A magnetic recording medium according to  claim 10 , wherein said soft magnetic granular layer is formed on said perpendicular magnetic recording layer, and said soft magnetic layer formed on said soft magnetic granular layer.  
     
     
         12 . The magnetic recording medium according to  claim 10 , wherein said the magnetic particles of soft magnetic layer contains as a main component at least one element selected from the group consisting of Fe, Co and Ni.  
     
     
         13 . The magnetic recording medium according to  claim 10 , wherein said nonmagnetic layer is formed of at least one element selected from the group consisting of B, C, Ti, Si, Al, Cr, Ru, Zr, Nb and Ta.  
     
     
         14 . A magnetic recording apparatus, comprising: 
 a magnetic recording medium having a nonmagnetic substrate, a perpendicular magnetic recording layer for recording signal, and a soft magnetic laminate layer formed between said nonmagnetic substrate and said perpendicular magnetic recording layer for recording signal, and including a soft magnetic layer which has a thickness not larger than 500 Å and a nonmagnetic layer;    driving means supporting and rotating the perpendicular magnetic recording medium;    a magnetic head including an element for recording information in the perpendicular magnetic recording medium and another element for reading the recorded information; and    a carriage assembly supporting the magnetic head such that the magnetic head is movable relative to the magnetic recording medium.    
     
     
         15 . A magnetic recording apparatus comprising: 
 a magnetic recording medium having a nonmagnetic substrate, a perpendicular magnetic recording layer, a soft magnetic laminate layer formed between the nonmagnetic substrate and the perpendicular magnetic medium, and including a first soft magnetic layer, and a second soft magnetic layer laminated on said first soft magnetic layer and differing from said first soft magnetic layer in the crystal structure;    driving means supporting and rotating the perpendicular magnetic recording medium;    a magnetic head including an element for recording information in the perpendicular magnetic recording medium and another element for reading the recorded information; and    a carriage assembly supporting the magnetic head and making the magnetic head be movable relative to the magnetic recording medium.    
     
     
         16 . A magnetic recording apparatus comprising: 
 a magnetic recording medium having a nonmagnetic substrate, a perpendicular magnetic recording layer, a soft magnetic laminate layer formed between the nonmagnetic substrate and the perpendicular magnetic medium, and including a soft magnetic granular layer formed of a nonmagnetic matrix and soft magnetic metal particles dispersed in said matrix, and a soft magnetic layer;    driving means supporting and rotating the perpendicular magnetic recording medium;    a magnetic head including an element for recording information in the perpendicular magnetic recording medium and another element for reading the recorded information; and    a carriage assembly supporting the magnetic head and making the magnetic head be movable relative to the magnetic recording medium.