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

Magnetic and recording characteristics of CoCrPt thin film media deposited on Cr75Ti25/CoTi double underlayers were investigated and compared to those on bare CoTi or Cr underlayer, Higher coercivity and improved SMR property were obtained compared to media that had CoTi or Cr underlayer, Transmissi on electron microscopy analysis showed that the crystal grain size and grai n size distribution in the magnetic layer were reduced when the Cr75Ti25/Co Ti double layer was used as underlayer. Furthermore, from the delta-M and m agnetic force microscopy analyses, it was found that CoCrPt/Cr75Ti25/CoTi t riple layered thin films had higher magnetic decoupling of neighboring grai ns than that of CoCrPt deposited on CoTi or Cr underlayer.