Information Degradation in Heated-Dot Magnetic Recording

Abstract

In this work, we focus on three factors as regards information degradation in 4 Tbpsi heated-dot magnetic recording, namely, (1) the reduction in readout field strength due to dot area variation, (2) the reversal of the magnetization direction during 10 years of archiving due to thermal fluctuation, and (3) during adjacent track writing due to thermal fluctuation (adjacent track interference, ATI). We consider the full width at half maximum of the readout field as well as the peak value. The bit error rate bER as a function of the minimum normalized readout field H0, that must be readable without error, is calculated using each dot error probability, taking account of dot area variation and thermal fluctuation. The H0 value needed to achieve a certain bER is determined by dot area variation. There is a minimum dot height for a certain bER, which is determined by thermal fluctuation. Even if the dot height is increased, the H0 value cannot be increased. Since temperature has a strong impact on dot error probability, a very large thermal gradient in the cross-track direction is needed to suppress ATI.