Magnetic recording medium

Abstract

The present invention relates to a magnetic recording medium for use in an external memory device of an information processing apparatus etc., and an object thereof is to reduce noise, achieve high coercive force, and use the substance as a magnetic recording medium for detecting signals in a magnetoresistance head. In the magnetic recording medium comprising the magnetic recording layer 25 including ferromagnetic grains 22 and a nonmagnetic substance 23 , the improvement in structure comprises that the ferromagnetic grains 22 are formed to have respectively an average grain diameter of 50 nm or less and not to be overlapped in the film thickness direction and to be isolated in the direction along a layer surface, and that a product of residual magnetization and a film thickness of the magnetic recording layer 25 is less than or equal to 150 Gauss•μm.

What is claimed is:  
     
       1. A magnetic recording medium comprising: 
       a magnetic recording layer including ferromagnetic grains and a nonmagnetic substance, said ferromagnetic grains including Fe, Co, Co x , Cr 100-x  (x is 90 or more), Co y Pt 100-y  (y is 70 or more, or 40 to 50), or Co A m 100-A  (A is 77.3, or 80 or more) as a major constant, said nonmagnetic substance including Ag or Cu as a major constituent;  
       wherein said ferromagnetic grains are formed to have an average grain diameter of 50 nm or less and not to be overlapped in the film thickness direction and to be isolated in the direction along a layer surface, and  
       wherein a product of residual magnetization and a film thickness of said magnetic recording layer is less than or equal to 150 Gauss•μm.  
     
     
       2. A magnetic recording device comprising: 
       a magnetic recording medium set forth in  claim 1 ; and  
       a magnetoresistance reproducing head.  
     
     
       3. A magnetic recording medium comprising: 
       a silicon substrate;  
       a first nonmagnetic layer formed of a silicon oxide layer on said silicon substrate, and including no magnetic grain grains therein; and  
       a second nonmagnetic layer formed on the same material as that of said first nonmagnetic layer on said first nonmagnetic layer, and including magnetic grains therein, said magnetic grains being formed of material which includes any at least one of selected from the group consisting of iron, cobalt, and nickel or at least one kind of them ; and  
       wherein a product of residual magnetization and a thickness of said second nonmagnetic layer which includes said magnetic grains therein is less than or equal to 150 Gauss•μm.  
     
     
       4. A magnetic recording device comprising: 
       a magnetic recording medium set forth in  claim 3 ; and  
       a magnetic head for reading and writing magnetic recording information from and into said magnetic recording medium.