Magnetic Fluctuations of Magnetic Disk Media

Abstract

The magnetic fluctuation on the rigid disk medium was derived from the medium noise spectrum by using the transfer function of the MR head. The spatial frequency (f_x) dependence of this fluctuation increases in the low and high f_x regions, and shows a similar tendency in both Co₈₆Cr₁₂Ta₂/Cr and Co₇₅Cr₁₃Pt₁₂/Cr media at the density range without interaction of magnetic transition between adjacent transitions. In the dc-demagnetized state, however, the magnetic fluctuation at low f_x is much larger for the CoCrTa/Cr medium than for the CoCrPt/Cr medium. Moreover, MFM observations showed larger magnetic clusters in the CoCrTa/Cr medium. Unlike in the CoCrPt/Cr medium, which has a structure with spatially separated grains, the continuous grain structure in the CoCrTa/Cr medium causes inter-granular effects, and the formation of large magnetic clusters.