Magnetic cluster and medium noise in CoCrTa/Cr longitudinal film media studied by magnetic force microscopy

The two-dimensional analysis method of magnetic force microscopy is proposed and applied to investigate magnetic cluster and medium noise in CoCrTa/Cr longitudinal film media. It is found that both the magnetic cluster size and root mean square (rms) noise intensity are dependent on recording density and the rms noise intensity strongly enhances with the increase of magnetic cluster size. To understand the factors that influence magnetic cluster formation, the magnetic cluster size, rms noise intensity and half-amplitude pulse width are plotted against tB(S)/H-c and delta M/M-S, respectively. It reveals that the increase of coercive force H-c and the reduction of intergranular magnetic interaction could control magnetic cluster size and decrease medium noise. The relationship between medium noise and residual magnetization fluctuation has been discussed. (C) 1999 American Institute of Physics. [S0021-8979(99)04102-X].