CPP-GMR Reader and Wraparound Shield Writer for Perpendicular Recording

摘要

Current-perpendicular-to-plane (CPP) giant magnetoresistive (GMR) read heads and wraparound shielded write heads for perpendicular recording were fabricated, and their recording performance was tested. The measured readout waveform of the CPP-GMR head was noise free and well biased. An output voltage of 2.2 mV and head-amp signal-to-noise ratio (SNR) of 30 dB were obtained from an operating voltage of 120 mV. Thermal damage in the heads was caused by an increase in the area of pinholes. The activation energy for the 5% resistance reduction was estimated to be 2.3 eV, which was similar to the self-diffusion energy of Co. The lifetime of the heads was projected to be 200 years. Newly developed CPP-GMR films showed the MR ratio of 6% at the resistance area product of 0.3 Ωμm{sup}2. The wraparound shielded write heads showed similar overwrite values to that of the unshielded heads. The shielded heads showed about 1 dB better media SNR and 5%-10% better linear resolution than the unshielded heads. Smaller side writing was found in the wraparound shield design, when the half-width of the off-track profile was the same. Better down-track and cross-track performance was thought to be due to a tighter field distribution in the shielded heads.