Investigations on adjacent-track interference in perpendicular recording systems

As areal densities increase and track-widths become narrower, adjacent-track interference (ATI) is becoming a major engineering concern in magnetic recording systems. In perpendicular recording, the nature of ATI is more complex due to the novel head designs and the soft underlayer. ATI arises when stray fields from the sides of a head cause erasure or create interference on an adjacent track. To uncover the sources of ATI in perpendicular systems, we developed a method using DC erase noise to identify the polarity as well as the extent and magnitude of the stray fields. This paper extends this earlier work to explain some of the puzzling phenomena that were observed and explores further the general ATI issues such as rate of signal decay with multiple writes and ultimately the impact on error-rate.