The effect of media properties on the longitudinal recording performance of particulate barium ferrite media

The influence of coercivity, remanent magnetization, and film thickness on the longitudinal recording performance of particulate barium ferrite media was investigated. Smooth, continuous films of longitudinal barium ferrite media were prepared with thicknesses, δ, of 0.10 to 0.25 μm. The coercivity, H_c, of the media varied from 674 to 1494 Oe, and the remanent magnetization, M_r, ranged from 68.0 to 83.9 emu/cm³. The recording properties were measured using heads with inductive-write and magnetoresistive-read elements. Regression analysis showed the following significant linear correlations (R⩾0.92): H_c with linear density (+), resolution (+), and overwrite (-); M _r with amplitude (+); and δ with linear density (-), resolution (-), overwrite (-), amplitude (+), RMS noise (+), and signal-to-noise ratio (+). Linear densities (-3 dB) of nearly 1500 fc/mm were achieved with high-coercivity, thin particulate media without equalization. These results are in agreement with magnetic recording theory and confirm the applicability of barium ferrite media for high-density magnetic recording. The surfaces of the substrate and underlayer have a pronounced influence on the magnetic and physical properties of the barium ferrite media, in particular, noise, surface topography, and film uniformity