Spike noise in soft under layer for perpendicular recording and its impact on error rate

Dual-layer perpendicular recording uses a magnetically soft under layer (SUL) beneath the recording layer to conduct the flux from the recording head. The required thickness of the SUL is determined by the SUL moment, the write pole moment and pole dimensions. Typically, the SUL thickness is from tens to a few hundred nanometers. Domains are often present in this thickness range. In this study, we examine in detail the properties of spike noise and assess the effect of spike noise on error rate.