The Effects of Write Pole Dimensions and Soft Underlayer Thickness on Perpendicular Magnetic Recording Performance

An examination of the recording process for perpendicular magnetic recording versus the soft under-layer thickness and write pole dimensions is provided. The recording performance is examined through an examination of SNR, transition jitter, di-bit pulse and others. A simple reluctance model, that incorporates the SUL along with the recording head in the magnetic circuit, is discussed which defines the minimum soft underlayer thickness required for optimal recording as Pt*Bspole/BsSUL, where the down-track write pole thickness is denoted as Pt and the magnetic flux density for the write pole material and the soft underlayer material are indicated as Bspole and BsSUL respectively. This model is experimentally confirmed, as we demonstrate that recording performance degrades with write pole thickness for Pt > tSUL*BsSUL/Bspole. However, the recording performance is found to be essentially independent of write pole width, also consistent with the model.