Offtrack characteristics of shielded magnetoresistive head

The shielded magnetoresistive (MR) head offtrack profile shows a wide output plateau which follows the conventional offtrack roll off curve. The authors investigated the origin of the unique offtrack characteristics and their influence on crosstalk signal-to-noise-ratio (SNR), based on experimental and magnetic calculation results. In the measurement, 8-μm track-width MR heads, consisting of a pair of 100-μm shields and a trilayered MR element between shields, were used. The plateau width is close to the shield width. The output in the plateau region is the sum of the contributed outputs from individual tracks under the shield. Therefore, this output can severely reduce the crosstalk SNR when the MR head includes several tracks under the shield. Magnetic calculation shows that the magnetic flux from the recorded track to the MR element through the shields can produce the output at the plateau region. Further examination shows that crosstalk SNR is improved by increasing the shield thickness and/or by decreasing the shield width. Therefore, to realize high track density, shield optimization is important