Read Spacing Loss in Perpendicular Magnetic Recording

The read spacing losses in perpendicular magnetic recording have been investigated experimentally for various combinations of heads and media. The spacing loss coefficient K, which is the slope of the line resulting when the spacing loss is plotted against d/¿, has been measured for sinusoidal magnetization. The results show that for a single layer medium, K is almost the same as that in longitudinal recording, and that for a double layer medium, the K value is large at long wavelengths and becomes small with decreasing wavelength. For ring heads in particular, a striking wavelength dependence of K is observed. Such a wavelength dependence results from the change in the distribution and the magnitude of the head sensitivity function with the spacing. Nevertheless, in digital recording the deterioration of recording density characteristics with increasing spacing is small, even at low densities, because of the contribution of harmonics in output signals.