Readback Spatial Sensitivity Function by Reciprocity Principle and Media Readback Flux

The sensitivity function is studied by using conventional reciprocity principle, and it is compared with the readback model's one, which is calculated as the read sensor output excited by the media recorded magnetization. These models are constructed by finite elements with finite permeability in a detailed three dimensional geometry. It is found that the sensitivity function of the reciprocity is different from one of the readback model, although it is believed that the sensitivity function should be equal to the read head field distribution. It is caused by the three dimensional structure, complicated media flux gathering of the sensor, and the media top and bottom magnetic charge effect. In addition to the sensitivity function difference, the reciprocity procedure is lack of sense of the media grain information, vector magnetization, and multilayered structure in the reproducing process. On the other hand, the developed readback model takes these features into account automatically.