Experimental studies of nonlinearities in high density disk recording

Nonlinear amplitude reduction in high-density disk recording has been studied. Dibit responses were measured at two flying heights, and disks with varying coercivity, magnetic moment, and substantially different noise levels were used. It is shown that the nonlinear amplitude loss is reduced substantially at lower flying heights. Increasing coercivity or decreasing magnetic moment similarly reduces this loss. Measurements of disks with different noise levels indicate more reduction for the low-noise medium only at the lower flying height. By deconvolving isolated pulses, transition lengths for single transitions were determined at each flying height. It is also found that the nonlinear amplitude reduction curves scale with transition length at a fixed flying height, indicating a universal curve