The role of SUL in readback and linear density limitation imposed

In perpendicular recording, soft underlayer (SUL) is critical for achieving a high field magnitude and large field gradient. Previous experimental and modeling studies have found that the presence of SUL significantly degrades the readback performance at high linear densities In this paper, the role of the SUL in readback is studied via a combined micromagnetic modeling and analytical investigation for obtaining a more complete understanding of the linear density limitations imposed.