The effect of spacing on demagnetization in magnetic recording

The effect of head to medium spacing on the magnetic recording process has been examined. For intimate contact recording, on flexible media, the record process is virtually demagnetization free to wavelengths at least as short as .8 μm. With spacings approximately .30 μm the spectral curves are proportional to the remanence at long wavelengths, but become demagnetization limited and coercivity dependent at wavelengths below about 1.6 μm. Spacings were obtained by sputtering Alfesil record and reproduce heads with a non-magnetic layer. Contact recordings with NiZn heads, which have been shown to possess a .25-.35 μm intrinsic "dead" layer, yield spectral curves which closely follow those obtained with Alfesil heads with 0.3 μm sputtered layers.