Analysis of Track-Edge Noise From the Viewpoint of Write Heads With Different Dimensions

Track-edge noise, which is one of the major hindrances in achieving the narrow track recording, was studied through spinstand testing and micromagnetics simulations. Three heads with different write pole widths were carefully chosen in the experiments so that their on-track head field gradients were almost similar, and the recording performance of these heads was evaluated with an identical narrow read head. Despite of their similar on-track field gradients, the narrowest write head exhibited a significantly low signal-to-noise ratio (SNR) at the track center. The reason for this is that the skirt of the reader sensitivity function contributed to an increase in noise even when the reader was at the center of the track. This experimentally observed track-edge noise effect on the on-track SNR was also confirmed through the micromagnetics simulations. The simulation results revealed that increasing the cross-track head field gradient effectively reduces the track-edge noise. A wraparound shield head is one of the promising candidates for narrow track recording because of its high cross-track head field gradient.