Distribution of coercivity and anisotropy through thickness direction in sputtered Co-Cr films and its relationship to noise characteristics in perpendicular magnetic recording

The relationship between c-axis orientation of crystallites and distribution of the perpendicular coercivity H_c⊥ in Co-Cr films has been investigated through the evaluation of the H_c⊥ of surface layer H_c⊥(s) measured by a Kerr hysteresis loop tracer. Better c-axis orientation, higher Cr content and addition of Ta seemed to be essential requirements to get higher H_c⊥ of initial growth layer H_c⊥(i) and good uniformity of H_c⊥ through the thickness direction. Lower ΔH_c and relatively high H_c⊥(i) caused better recording characteristics and lower media noise level