Amplitude and bit shift spectra comparisons in thin metallic media

Signal and bit shift measurements have been made on a variety of thin metallic media. The high density outputs increase monotonically with coercivity while an optimum occurs for a thickness variation. At 80 KFRPI a 900 Oe 1.1μ" disc exceeds a conventional oxide disc in signal by 30 dB for small head-medium spacings. Bit shift measured on a MFM 11011011 pattern is always less than that given by linear superposition. For small spacings 15% bit shift occurs @ 72 KFRPI for the 900 Oe disc compared to 15 KFRPI for the oxide.