Off-track margin in bit patterned media

When two dimensional patterns are written into bit patterned media the off-track margin is of great importance. Using a static write/read tester we measure the hard error rate (written-in errors) as a function of the distance from the track center. We observe three different segments. In the track center, the head writes very well and almost no hard errors are observed. At the track edges the hard error rate increases linearly over an interval, which is shown to relate to the off-track margin of the recording system. At larger distances from the track center, no islands are switched.