Effect of Media Reversal Mode on Head Footprint

Using a ldquodragrdquo tester in which the recording head is in direct contact with a perpendicular media disc, we show experimentally that the footprint of the head has a ldquodoughnutrdquo shape, as predicted by theory. A change in the switching properties of the media, from coherent rotation in conventional perpendicular media to incoherent rotation in exchange spring media, can be detected through the transformation of the head footprint, from ldquodoughnutrdquo to a dome-like shape.