Quang Le

The effect of a trailing shield for perpendicular write heads

The effect of a magnetic trailing shield located in close proximity of the pole tip for a perpendicular write head has been studied in a perpendicular recording system. For a 150nm wide write pole, the write field gradient is improved yielding a 40% decrease in jitter and 2.2dB increase in the signal-to-noise ratio (SNR). As the pole width is narrowed further, modeling and experiments show that the trailing shield leads to a tradeoff between maintaining a high write field (writeability) and achieving an optimal write field gradient (jitter). For a 70nm writer, the addition of a trailing shield results only in a small 0.5dB SNR gain despite a 25% decrease in jitter as a result of the concomitant loss in writeability. The latter results in an increased dc noise and becomes more significant with trailing shield throat thickness.