A double underlayer for Co-based longitudinal recording thin film media

Magnetic and recording characteristics of CoCrPt thin film media deposited on Cr/sub 75/Ti/sub 25//CoTi double underlayers were investigated and compared to those on bare CoTi or Cr underlayer. Higher coercivity and improved SNR property were obtained compared to media that had CoTi or Cr underlayer. Transmission electron microscopy analysis showed that the crystal grain size and grain size distribution in the magnetic layer were reduced when the Cr/sub 75/Ti/sub 25//CoTi double layer was used as underlayer. Furthermore, from the delta-M and magnetic force microscopy analyses, it was found that CoCrPt/Cr/sub 75/Ti/sub 25//CoTi triple layered thin films had higher magnetic decoupling of neighboring grains than that of CoCrPt deposited on CoTi or Cr underlayer.