On the readback resolution of the single pole heads

A theory is proposed to clarify contradictory results on the readback resolution of a single-pole head when it is combined with the double-layer perpendicular recording media. The method starts by examining the magnetization distribution inside the read head. The general reciprocity principle is rederived from a series of reciprocity theorems developed many years ago for ferromagnetism, and another kind of reciprocity principle relating the readback voltage directly the magnetization state in the read head is introduced. A novel algorithm is developed for analyses based on the principles, and the results of the initial calculations are given. The predicted readback resolution can be much better than those implied in earlier theories