Magnetic force scanning tunneling microscope imaging of overwritten data

The MFSTM (magnetic force scanning tunneling microscopy) technique is shown to be a powerful technique for generating images of magnetization patterns. Images of the overwritten data on commercial magnetic disks and images of deliberately written patterns which serve as benchmark are presented. The usefulness of this method for probing the subtle effects of insufficient erasure during data overwrite. Results demonstrate that, due to the limitations in the electromechanical positioning of the recording head, overwritten data in longitudinal rigid disk recording systems are not necessarily completely erased. As a result, portions of the old data remain and could be retrieved. In the future, this technique can provide some valuable insights into various mechanisms associated with data overwrite, which include questions about the minimum off-track deviation necessary before the old data can persist.<
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