Recording head characterization using 1 μm wide discrete tracks

Discrete tracks ~1-μm wide etched on the surface of a Co-alloy disk were used to determine the readback response of thin-film recording heads at various locations across the width of a head. The effective head width for readback decreases as the recording density increases and shows several small maxima for densities greater than 600 flux-reversals/mm. The location of these maxima is determined by the thickness of the pole tips. The shape of the frequency dependence of the readback amplitude (rolloff curve) changes considerably near the edges of the pole tips. A qualitative description of this behavior is presented using calculations from a three-dimensional model. The influence of edge effects due to unequal pole-tip widths is observed when rolloff curves on conventional media are compared with data acquired using a narrow discrete track