Method and Manufacture Process for Exchange Decoupled First Magnetic Layer

Abstract

A perpendicular magnetic recording medium having a dual-layer magnetic film is disclosed. The bottom layer is completely exchange decoupled, and the top layer contains a certain amount of exchange coupling optimized for recording performance. Preferably, the bottom magnetic layer contains stable oxide material (for example, TiO 2 ) and other non-magnetic elements (for example, Cr). A method of manufacturing the media is also disclosed.

1 - 20 . (canceled) 
     
     
         21 . An apparatus, comprising:
 a substrate of a magnetic recording medium; and   a granular magnetic layer of the medium, wherein the granular magnetic layer comprises one or more first layers being substantially completely exchange decoupled and one or more second layers being partially exchange coupled, wherein the one or more first layers have an H c  of greater than about 4,000 Oe and an H n  of less than about 0.25 H.   
     
     
         22 . The apparatus of  claim 21 , wherein the one or more first layers have an H c  of greater than about 6,000 Oe and an H n  of less than about 1,000 Oe. 
     
     
         23 . The apparatus of  claim 21 , wherein the one or more first layers comprise an oxide material in an amount of about 4 to about 12 mol %. 
     
     
         24 . The apparatus of  claim 23 , wherein the oxide material is TiO 2 . 
     
     
         25 . The apparatus of  claim 21 , wherein the one or more first layers comprise a non-magnetic element. 
     
     
         26 . The apparatus of  claim 25 , wherein the non-magnetic element is present in an amount of about 4 to about 20 mol %. 
     
     
         27 . The apparatus of  claim 25 , wherein the non-magnetic element is Cr. 
     
     
         28 . The apparatus of  claim 21 , wherein a composition of at least one of the first layers is CoCr x Pt y —(TiO 2 ) z , wherein x has a value of from 4 to 20, y has a value of from 12 to 25, and z has a value of from 4 to 12. 
     
     
         29 . The apparatus of  claim 28 , wherein the composition is CoCr 10 Pt 18 —(TiO 2 ) 6 . 
     
     
         30 . The apparatus of  claim 21 , wherein the one or more second layers are substantially free of oxide material. 
     
     
         31 . An apparatus, comprising:
 a substrate of a magnetic recording medium; and   a granular magnetic layer of the medium, wherein the granular magnetic layer comprises one or more first layers being substantially completely exchange decoupled and one or more second layers being partially exchange coupled, wherein an exchange coupling of the granular magnetic layer is tuned by varying a thickness of the one or more second layers, and wherein the one or more first layers have an H c  of greater than about 4,000 Oe and an H n  of less than about 0.25 H c .   
     
     
         32 . The apparatus of  claim 31 , wherein separation between grain boundaries of the one or more second layers is tuned to achieve a substantially uniform, controlled value of exchange coupling strength for the granular magnetic layer. 
     
     
         33 . The apparatus of  claim 31 , wherein the one or more first layers have an H c  of greater than about 6,000 Oe and an H n  of less than about 1,000 Oe. 
     
     
         34 . The apparatus of  claim 31 , wherein the one or more second layers are substantially free of oxide material. 
     
     
         35 . The apparatus of  claim 31 , wherein the one or more first layers comprise a non-magnetic element. 
     
     
         36 . The apparatus of  claim 31 , wherein a composition of at least one of the first layers is CoCr x Pt y —(TiO 2 ) z , wherein x has a value of from 4 to 20, y has a value of from 12 to 25, and z has a value of from 4 to 12. 
     
     
         37 . An apparatus, comprising:
 a substrate;   one or more soft underlayers;   one or more seed layers;   one or more interlayers;   a granular magnetic recording layer; and   one or more cap layers, wherein the granular magnetic layer comprises one or more first layers being substantially completely exchange decoupled and one or more second layers being partially exchange coupled, wherein the one or more first layers have an H c  of greater than about 4,000 Oe and an H n  of less than about 0.25 H c .   
     
     
         38 . The apparatus of  claim 37 , wherein an exchange coupling of the granular magnetic layer is tuned by varying a thickness of the one or more second layers. 
     
     
         39 . The apparatus of  claim 37 , wherein the one or more first layers have an H c  of greater than about 6,000 Oe and an H n  of less than about 1,000 Oe. 
     
     
         40 . The apparatus of  claim 37 , wherein the one or more second layers are substantially free of oxide material.