MAGNETIC IMAGING IN THE PRESENCE OF EXTERNAL FIELDS - TECHNIQUE AND APPLICATIONS

Magnetic force microscopy (MFM) in the presence of an external magneti c field has been developed. This has led to further understanding of i mage formation in MFM as well as new insights concerning the interacti on of magnetic recording media with an external field. Our results con firm that, at low applied fields, image formation results from the int eraction of the component by the local surface field along the directi on of the probe's magnetization. By reorienting the probe's magnetizat ion by an appropriate application of an external field, it is possible to selectively image specific components of the local field. At highe r applied fields, the probe becomes saturated and the changes in the i mages may be attributed to magnetization reversal of the sample. We ha ve observed the transformations that occur at various stages of the de erasure of thin-film recording media. This technique has also been ap plied to conventional magneto-optical media to study domain collapse c aused by increasing temperature with an external bias field. The metho ds, results, and their analysis are presented. (C) 1996 American Insti tute of Physics.