Probabilities of Transition Jitter at Different Off-Track Positions

Abstract

Current typical perpendicular commercial media has grain size of around 8 nm, which the size has remained more or less the same since its introduction. Typical bit lengths for the media can go as low as 15-20 nm. Transition jitter, which is one type of media noise, tends to occur at regions where magnetic transitions could be found. Such noise could affect the storage and readability of the data, especially as more accuracy is demanded when hard disk industries push for higher and higher densities. This work describes the methodology of using averaging methods to measure the writer footprints jitter profiles which are recorded at different writing currents on a Spinstand. Two different commercial heads have been used for the evaluation. Multiple down-track footprint averaging and least square fitting of the individual transition footprint data against the noise-free footprint are used to retrieve the jitter profiles of the writers at different writing conditions. The statistical jitter profiles are then used to plot various cross-tracks and regionalized jitter distribution and probability plots. From the plots, it is quite conclusive to determine that writer A at 50 mA especially at the track center (TC) has the minimal and thus best jitter profile amongst the other writing conditions and heads used.