The role of SUL in readback and effect on linear density performance for perpendicular recording

We present a micromagnetic modeling on the readback process of perpendicular recording with soft underlayer (SUL). The effect of the SUL on readback has been investigated. The SUL imaging effect enhances the readback signal amplitude differently for high density and low density, making the rolloff of the readback signal faster with the linear density and, thus, deteriorating the readback performance by lowering the maximum achievable linear density. Most approaches for increasing the density limit via making the SUL imaging less effective are accompanied by the tradeoff of the write field loss. Reducing the head-medium spacing and the reader gap with an optimized spin valve reader stripe height are essential for maximizing the linear density limits imposed by the rolloff of the readback.