Abstract
Head sensitivity function of MR heads for perpendicular double layer media was derived for the sake of the head response calculations by reciprocity theorem. Approximated Fan's function was given. Comparisons with the exact solution showed the validity of the function. Hyperboric tangent function and error function also agreed well with the Fan's solution. However, for the agreement with expermental results, assumption of an extremely narrow transition length of recorded magnetization, i.e. less than 10 nm or almost zero, was required. Further investigation would be needed for this point. Noise spectrum could also be explained by the obtained head sensitivity finctions.
