Perpendicular magnetic recording medium

Abstract

Embodiments of a perpendicular magnetic recording medium include: a base; at least a first magnetic recording layer having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a non-magnetic split layer containing Ru disposed on the first magnetic layer; and a second magnetic recording layer that is disposed on the split layer and that has a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape, wherein the first magnetic layer and the second magnetic layer contain oxides that form the grain boundary, and when an oxide content of the first magnetic layer is represented by A and an oxide content of the second magnetic layer is represented by B, a relationship between the oxide contents A/B is in the range of 0.5<A/B<1.0.

1 . A perpendicular magnetic recording medium, comprising:
 a base;   a first magnetic layer having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape;   a first split layer disposed on the first magnetic layer;   a second magnetic layer that is disposed on the first split layer and that has a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape;   a second split layer disposed on the second magnetic layer; and   a third magnetic layer that is disposed on the second split layer and that is magnetically approximately continuous in an in-plane direction of a main surface of the base.   
     
     
         2 . The perpendicular magnetic recording medium according to  claim 1 , wherein the first or second split layer is composed of Ru or a Ru alloy. 
     
     
         3 . The perpendicular magnetic recording medium according to  claim 1 , wherein the first or second split layer further contains oxygen or an oxide. 
     
     
         4 . The perpendicular magnetic recording medium according to  claim 3 , wherein the first or second split layer is RuO, RuWO 2 , or RuTiO 2 . 
     
     
         5 . The perpendicular magnetic recording medium according to  claim 1 , wherein the thickness of the first or second split layer is in a range of 2 Å to 10 Å. 
     
     
         6 . The perpendicular magnetic recording medium according to  claim 1 , wherein the thickness of the first magnetic layer is 5 nm or less. 
     
     
         7 . The perpendicular magnetic recording medium according to  claim 1 , wherein the first magnetic layer is in a range of 0.7 nm to 3.0 nm in film thickness. 
     
     
         8 . The perpendicular magnetic recording medium according to  claim 1 , wherein the first magnetic layer contains 5 mol % or more of oxide constituting the grain boundary portion. 
     
     
         9 . The perpendicular magnetic recording medium according to  claim 1 , wherein the second magnetic layer contains 5 mol % or more of oxide constituting the grain boundary portion. 
     
     
         10 . The perpendicular magnetic recording medium according to  claim 1 , wherein the second magnetic layer contains two or more kinds of oxides. 
     
     
         11 . The perpendicular magnetic recording medium according to  claim 1 , wherein the second magnetic layer contains one or plural oxides selected from a group consisting of SiO 2 , TiO 2 , and CoO.