Effects of write current switching time on recording characteristics (abstract)

Abstract

High-frequency recording is essential for a recording channel with both a high data rate and a high linear recording density, and this study examined the ways in which performances are affected by the switching time of the write current, ts, and the disk velocity, v. The switching time, defined as (tr+tf)/2, where tr and tf are the rise time and the fall time of the write current, was changed from 5 to 20 ns, while v was changed from 12 to 26 m/s. Co-based thin-film media with a coercivity of about 2.5 kOe and a remanence-thickness product of about 100 G μm were used for recording the data. The flying height of the head was maintained at 50 nm regardless of disk velocity. This study confirmed that the overwrite characteristics are strongly related to the product of ts and v. Overwrite here was defined as the ratio of the residual fundamental frequency component amplitude of a 21 kFCI signal to the original one after overwriting with a 86 kFCI signal. Suitable overwrite characteristics were obtained when t*sv was smaller than πa, where a is the transition parameter derived from the equation proposed by Williams and Comstock. The transition length on the medium was determined primarily by πa when t*sv was smaller than πa, but was determined by t*sv when t*sv was larger than πa. Linear density characteristics and noise characteristics and their relationship to the medium properties will also be addressed in this talk.