Time Dependence of Magnetic Properties in Perpendicular Recording Media

Naoki HONDA  Kazuhiro OUCHI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.9   pp.1180-1186
Publication Date: 1997/09/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on High Density Information Recording Technologies)
Category: 
Keyword: 
time decay of magnetization,  perpendicular media,  demagnetizing field,  squareness,  time decay in output,  

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Summary: 
Time decay of magnetic properties in perpendicular magnetic recording media was studied. It was suggested that magnetization in media with a low energy ratio, KV/kT, of 50 is thermally stable in the absence of a demagnetizing field while coercivity exhibits a large time dependence. Magnetization in perpendicular recording media exhibited an appreciable time decay even for films with a large energy ratio of 300. The decay is attributed to the small perpendicular squareness due to a large perpendicular demagnetizing field acting in the media. The recording density dependence of the time decay in the output was explained in terms of the change in the demagnetizing field with the density. It is concluded that the use of media with large squareness as well as large energy ratio effectively reduces time decay in the output.