CoCrPtB alloys with increased boron content and method of producing same

Abstract

A magnetic layer structure with a layer of cobalt-chromium-platinum-boron composite alloy containing 10% to 20% B in the magnetic layer. The useful magnetic properties of the magnetic layer structure are achieved by the incorporation of a nucleation layer prior to the deposition of the magnetic layer. The resultant magnetic layer structures have coercivity H c values in between 2,000 and 5,000 Oe, grain sizes between 30 and 200 Angstroms and anisotropic crystallographic orientation with the c-axis of the cobalt-chromium-platinum-boron in the plane of the medium. These magnetic layer structures are suitable for magnetic data storage devices including magnetic disks.

What is claimed is:  
     
       1. A magnetic recording medium comprising a magnetic layer 10 to 50   5  to  500 Angstroms thick, said magnetic layer comprising a Co alloy comprising Cr x , Pt y , and B z  wherein 0≦x≦30, 0≦y≦40 and 10≦z≦25   10 <z≦ 25 atomic percent, and 25≦(x+y+z)≦60, said magnetic layer having a coercivity value ranging between 2000 and 5000 Oe. 
     
     
       2. The medium of  claim 1  wherein said magnetic layer is a magnetic layer in a multi-layer magnetic structure. 
     
     
       3. A magnetic recording medium comprising: 
       a) a substrate;  
       b) a metal under-layer on said substrate said, under-layer having a body-centered-cubic lattice structure;  
       c) a Co alloy nucleation layer deposited on said under-layer wherein said Co alloy nucleation layer is 1 to 50 Angstroms thick;  
       d) a magnetic layer deposited on said Co alloy nucleation layer, said magnetic layer comprising a Co alloy comprising Cr x , Pt y , and B z  wherein 0≦x≦30, 0≦y≦40 and 10≦z≦25 atomic percent, and 25≦(x+y+z)≦60.  
     
     
       4. The medium of  claim 3  wherein said substrate is selected from the group consisting aluminum with a plated nickel phosphorus coating, glass, silicon, ceramic and quartz. 
     
     
       5. The medium of  claim 3  wherein said media substrate is a disk substrate. 
     
     
       6. The medium of  claim 3  wherein said under-layer is selected from the group consisting of chromium, ruthenium, chromium alloy and ruthenium alloy. 
     
     
       7. The medium of  claim 6  wherein said under-layer has a substantially crystallographic [100] orientation. 
     
     
       8. The medium of  claim 6  wherein said under-layer has a substantially crystallographic [110] orientation. 
     
     
       9. The medium of  claim 6  wherein said under-layer is deposited by a process selected from the group consisting of sputtering, ion-beam deposition and laser deposition. 
     
     
       10. The medium of  claim 3  wherein said Co alloy nucleation layer is comprised of CoCr x Pt y B z , wherein 15≦x≦40, 0≦y≦15 and 0≦z≦10 atomic percent, and 25≦(x+y+z)≦50. 
     
     
       11. The medium of  claim 10  wherein said magnetic layer contains grain sizes ranging from 20 to 200 Angstroms. 
     
     
       12. The medium of  claim 11  wherein said magnetic layer has a thickness ranging from 5 to 500 Angstroms. 
     
     
       13. The medium of  claim 12  wherein said magnetic layer is deposited by a process selected from the group consisting of sputtering, ion-beam deposition and laser deposition. 
     
     
       14. The medium of  claim 6  wherein said medium has a coercivity value ranging between 2000 and 5000 Oe. 
     
     
       15. A method for making a magnetic storage medium comprising: 
       a) providing a substrate;  
       b) depositing on said substrate an under-layer selected from the group consisting of chromium, ruthenium, chromium alloy and ruthenium alloy;  
       c) depositing on said under-layer a nucleation layer comprising a Co alloy comprising Cr x , Pt y , and B z  wherein 15≦x≦40, 0≦y≦15 and 0≦z≦10 atomic percent, and 25≦(x+y+z)≦50;  
       d) and depositing on said nucleation layer a magnetic layer comprising a Co alloy comprising Cr z , Pt y , and B z  wherein 0≦x≦30, 0≦y≦40 and 10≦z≦25 atomic percent, and 25≦(x+y+z)≦60.  
     
     
       16. The method of  claim 15  wherein providing said substrate comprises providing a substrate selected from the group consisting of aluminum with a plated nickel phosphorus coating, glass, silicon, ceramic and quartz. 
     
     
       17. The method of  claim 15  wherein said nucleation layer is deposited to a thickness ranging from 1 to 100 Angstroms. 
     
     
       18. The method of  claim 15  wherein said nucleation layer is deposited by a process selected from the group consisting of sputtering, ion-beam deposition and laser deposition. 
     
     
       19. The method of  claim 15  wherein said magnetic layer is deposited to a thickness ranging from 5 to 500 Angstroms. 
     
     
       20. The method of  claim 15  wherein said magnetic layer is deposited by a process selected from the group consisting of sputtering, ion-beam deposition and laser deposition. 
     
     
       21. The method of  claim 15  wherein depositing said under-layer includes applying a negative electrical bias to said substrate.