Additional Reader Noise in TDMR Reader for ITI Cancelation

Abstract

Shingled writing eliminates the writer width limitation and enables further bit aspect ratio reduction to extend the areal density growth of current perpendicular magnetic recording. The achievable track density of shingled magnetic recording (SMR) is determined by the reader width rather than the writer width. However, continuously scaling of reader width increases the reader resistance and results in higher reader noise. It would be an issue to maintain enough signal-to-noise ratio of reader. The 2-D magnetic recording (TDMR) was proposed to extend the density growth by advanced signal processing technique. In TDMR configuration, there are multiple readers to read multiple tracks simultaneously. Recently, the TDMR reader was proposed as a solution of intertrack interference cancelation, which allows to use wider reader to reproduce signals from narrow tracks. In this paper, an additional reader noise is observed when the reader was positioned to read two tracks at the same time. The formation of the reader sensor appears to be closely related to the current reader structure with hard bias magnet. This issue highlights that a solution is required to enable TDMR, probably a reader structure without hard-biased.