Magnetic properties and domain patterns of CoCrPtTa perpendicular films with Ta content

The effects of Ta addition or the magnetic properties and domain types in C oCrPtTa were investigated from magnetic force microscopy images and M-H hys teresis loop shapes. A third element is added to the CoCr binary system bec ause high coercivity cannot be obtained from the CoCr binary system. The ad dition of Pt increases coercivity because of the contribution of the magnet ocrystalline anisotropy effect. However, CoCrPt also shows increased media noise due to larger magnetic couplings between columnar grains. For the pur pose of avoiding this drawback, magnetic isolation between columnar grains should be attempted, and Cr segregation contributes to this attempt. In add ition to magnetic isolation, Ta addition to CoCr is known to enhance Cr seg regation. The magnetic isolation between columnar grains of the Co alloy is affected by the segregation of non-magnetic solute atoms. Addition of Ta t o CoCrPt shows that the magnetic domain changes from a continuous to a dot- like pattern with increases of Ta content. This indicates that Ta addition weakens the inner segregation of other non-magnetic solute atoms such as Pt or Cr, while it strengthens grain boundary segregation, which leads to the benefit of noise reduction in the high density recording media. (C) 2001 E lsevier Science B.V. All rights reserved.