Signal-to-noise ratio studies on γ-Fe2O3thin film recording disks

The signal-to-noise ratio SNR
w
of γ-Fe
2
O
3
thin film disks has been investigated in a linear bit density range of 77-1500 flux reversals per millimeter (FRPM), for several media whose average crystallite sizes were changed by Ti doping. The noise voltage was found to increase as the bit-cell length became shorter, and as the average crystallite size became larger. A SNR
w
relationship to the average crystallite size, the resolution, and the bit-cell length was empirically determined as a simple formula. For a 10-μm core width and for a 1.0-μm bit-cell length, an SNR
w
of more than 35 dB was estimated to be attainable from the medium which had a 0.90 resolution and had crystallites averaging less than 0.06 μm in size.