Magnetic thin film media with a pre-seed layer of CrTi

Abstract

The applicants disclose a thin film magnetic media structure with a pre-seed layer of CrTi. The CrTi pre-seed layer presents an amorphous or nanocrystalline structure. The preferred seed layer is RuAl for use with the CrTi pre-seed layer. The use of the CrTi/RuAl bilayer structure provides superior adhesion to the substrate and resistance to scratching, as well as, excellent coercivity and signal-to-noise ratio (SNR) and reduced cost over the prior art. One embodiment of the invention sputter-deposits a CrTi pre-seed layer and a RuAl seed layer followed by an underlayer and at least one magnetic layer on a circumferentially polished substrate structure to achieve an Mrt orientation ratio greater than one. Two methods according to the invention allow the Mrt orientation ratio of the disk to be adjusted or maximized by varying the thickness of the RuAl seed layer and/or altering the atomic percentage of titanium in the pre-seed layer.

1 . A magnetic thin film disk comprising: 
 a circumferentially textured glass substrate structure;    a layer of CrTi deposited on the substrate;    a seed layer of RuAl with a B2 crystallographic structure over the layer of CrTi;    an underlayer over the seed layer; and    at least one magnetic layer over the underlayer, the magnetic layer having an Mrt orientation ratio greater than one and having a crystallographic orientation with c-axis in-plane for longitudinal recording.    
     
     
         2 . The magnetic thin film disk of  claim 1  wherein the CrTi layer has from 35 to 90 at. % Ti.  
     
     
         3 . The magnetic thin film disk of  claim 1  wherein the CrTi layer has approximately from 43 to 85 at. % Ti.  
     
     
         4 . The magnetic thin film disk of  claim 1  wherein the CrTi layer is amorphous or nanocrystalline.  
     
     
         5 . The magnetic thin film disk of  claim 1  wherein the CrTi layer is approximately from 10 to 100 nm thick.  
     
     
         6 . The magnetic thin film disk of  claim 1  wherein the circumferentially textured substrate structure has an Rq from 2 to 20 angstroms.  
     
     
         7 . The magnetic thin film disk of  claim 1  wherein the Mrt orientation ratio is greater than 1.1