As recording density increases rapidly in recent yeairs, high coercivity and iow noise media became more an important issue in perpendicular as well as longitudinal recording media. Compare to CoCr, CoCrTa system is more effective in increasing coercivity by enhancing Cr segregation into column boundaries. There was no improvment in C-axis alignment in the case of CoCrTa when Ti underlayer was used. In the case of CoCrPt case, when Pt content is lower, coercivity was not improved and M-H curve

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... howed more domain wall motion type reversal indicating rather strong magnetic coupling among celumns, When Ta is added in CoCrPt, coercivity increased and M-H curve showed domain wall motion type behavior was reduced, which must be associated with Cr segregation to boundary by Ta addition.