Abstract
Effects of negative d.c. substrate bias on the film properties of CoCrTa/Cr magnetic recording media have been investigated. When the substrate bias was increased from zero to -250 V, the Ta content was found to increase from 3.9 to 15.0 at.%, whereas the Cr content decreased and the deposition rate was reduced. X-ray diffraction (XRD) analysis revealed the replicate growth of Co (112̄0) on the Cr (002) plane. The peak shift and line broadening of Co (112̄0) diffraction are attributed to the compositional change and presence of residual stress in the deposited film. The occurrence of maximum coercivity at -150 V bias is correlated to the formation of structural defects. However, too high a bias (-250 V) induces formation of an excessive amount of weak magnetic phase, which causes the magnetic properties to deteriorate. The enhancement of the coercivity due to substrate bias is primarily governed by hindrance of domain wall motion by structure defects and/or residual stress.