Performance of NiO spin-valve tape heads for high recording densities

Abstract

Shielded NiO biased spin-valve tape heads with permanent magnet stabilization are described. Heads with 5 and 9 μm trackwidths, shield-to-shield spacing of 0.43 and 0.53 μm, and height of 1 μm are characterized on DLT–IV tape (0.2 μm magnetic thickness, Hc=1850 Oe, Mr.δ=6.5 memu/cm2) up to 150 kfci. Maximum head output is ∼1 mVpp/μm (3–5 mA sense current), decaying to a maximum of 23 μVpp/μm at 150 kfci (the 40–150 kfci resolution is 5%), with signal loss with linear density of 0.34 dB/kfci. Distortion level is ∼−33 dB for second and third harmonics at high linear density. Harmonic distortion above −20 dB is observed for linear density under 60 kfci due to partial head saturation. Head output is compared with a linear model. This model is used to predict head performance with smaller gaps (calculated resolution increases to 35% with 500 Å half-gap, but head efficiency decreases) and with thinner, smoother media (calculated output level at 150 kfci increases by 13 dB, and resolution increases to 14%).