Direct probe of anisotropy field dispersion in perpendicular media

A complex transverse alternating-current (ac) susceptibility ( χ T ) technique based on magneto-optical detection has been developed with sufficient sensitivity for thin film recording media. The technique has been used to measure the dispersions in grain size and anisotropy field in perpendicular m...

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Bibliographic Details
Published in:Journal of applied physics 2006-04, Vol.99 (8), p.083902-083902-4
Main Authors: Ju, Ganping, Zhou, Hong, Chantrell, Roy, Lu, Bin, Weller, Dieter
Format: Article
Language:English
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Summary:A complex transverse alternating-current (ac) susceptibility ( χ T ) technique based on magneto-optical detection has been developed with sufficient sensitivity for thin film recording media. The technique has been used to measure the dispersions in grain size and anisotropy field in perpendicular magnetic recording media. Applying a direct-current (dc) field perpendicular to the easy axis effectively reduces the thermal energy barrier, which leads to thermally activated switching on the time scale of the ac field applied in the easy-axis (perpendicular) direction. The dc field dependence of the resulting imaginary transverse ac susceptibility Im ( χ T ) is sensitive to dispersions in both the grain size and the anisotropy field. The sensitivity has been used to extract the amount of both dispersions. It has been found that the extracted grain size dispersion values agree well with those obtained from plane-view transmission electron microscopy micrographs.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.2189025