SPECTRUM ANALYSIS OF RECORDED MAGNETIZATION USING MAGNETIC FORCE MICROSCOPY

Spectrum analyses of recorded magnetization were performed using magnetic force microscopic (MFM) images to quantitatively analyze the relationship between the magnetization structure and the reproduced signal output. Repeated one-dimensional Fourier analyses were performed on an MFM image along the recording direction of the disk medium for a certain width with a pitch of about 70 nm. The dependence of MFM signal intensity on wavelength was obtained through Fourier transformation. Differences in the noise characteristics of CoCrTa media with different Cr compositions were investigated. Several peaks in the Fourier-transformed spectrum are related to the magnetic cluster size and/or the magnetic cross-linking distance between neighboring recorded bits. The magnetic interactions were found to extend up to about 0.5 mu m and 1 mu m for magnetically recorded CoCr16Ta4 and CoCr10Ta4 media, respectively.