Downtrack response of differential reader for high density magnetic   recording
  The downtrack responses of a differential reader to various magnetic patterns have been investigated micromagnetically. The differential signals can well discriminate the "0" and "1" readback bits and the waveforms obtained resemble the counterparts for longitudinal media or for perpendicular media after differentiation. Pulse shapes are found Gaussian. With decreasing head media spacing, free layer thickness, and gap length, PW50 roughly linearly decreases and the maximum signal exponentially increases. These properties, together with small inter-symbol interference, are essential for future high density magnetic recording. 
Li Wang, Guchang Han
cond-mat.mtrl-sci