Spacing Modulation of Magnetic Head Due to Topographical Feature of Disk Surface

Abstract

To achieve high recording density, the combination of low flying head and smooth disk surface is very desirable. Although high stiction associated with the smooth surface can be avoided by zone texturing or ramp load, stable flying condition must be assured by a smooth disk surface. Disk topography is an important factor in the flying stability of the head. In this work, read back signal modulation analysis was incorporated to characterize the disk topography. By increasing the writing frequency up to 25 MHz , high resolution was demonstrated in the fly height range between 15 nm to 50 nm. This resolution is sufficient to evaluate today’s low flying heads. A subambient pressure design which is typical for an MR head and a proximity head design for an inductive head were evaluated over very smooth aluminum disks. The effect of various disk clamping forces was also investigated. Relationship between disk waviness and flying stability of heads was studied.