Influence of the layer thickness of a double-layer medium on the reproduced signal in perpendicular recording

The influence of the thickness of the layers in a single-layer or double-layer medium and of the permeability of the backlayer on the reproduced signal in perpendicular recording is investigated theoretically. With the aid of the reciprocity theorem of magnetic recording the harmonic response is calculated. For a highly permeable isotropic backlayer, the influence of its thickness proves to be small.