Medium SNR and Sharpness of Micro-Track Profile of CPP-Type Head With an Arbitrary Magnetic Shield Shape

Current perpendicular to plane (CPP)-type heads having various magnetic shield shapes were fabricated, and their medium signal-to-noise ratios (SNRs) and micro-track profiles (MTPs) were measured. To find out how to improve the sharpness of an MTP, we calculated the relationship between a magnetic read width (MRW) and a magnetic shield shape and a shield-to-shield gap spacing (Gs). In our calculation based on the reciprocity principle, a nonuniform magnetic potential reflecting the sensitivity in the free layer was introduced to give a precise MTP. The calculation indicates that a narrow Gs and a parallel shield are effective in obtaining a sharper MTP. The calculation results were also confirmed by experimental data. Measurement using a perpendicular medium shows that the medium SNR gets higher as the MTP becomes sharper. Thus, CPP-type heads with a sharp MTP have an advantage in getting good SNR performance