Magnetic cluster and medium noise in CoCrTa/Cr longitudinal film media studied by magnetic force microscopy

Abstract

The two-dimensional analysis method of magnetic force microscopy is proposed and applied to investigate magnetic cluster and medium noise in CoCrTa/Cr longitudinal film media. It is found that both the magnetic cluster size and root mean square (rms) noise intensity are dependent on recording density and the rms noise intensity strongly enhances with the increase of magnetic cluster size. To understand the factors that influence magnetic cluster formation, the magnetic cluster size, rms noise intensity and half-amplitude pulse width are plotted against tBS/Hc and δM/MS, respectively. It reveals that the increase of coercive force Hc and the reduction of intergranular magnetic interaction could control magnetic cluster size and decrease medium noise. The relationship between medium noise and residual magnetization fluctuation has been discussed.

Magnetic properties, magnetic cluster size, and read-write performance of CoPtCr-SiO/sub 2/ perpendicular recording media

“…4 shows the magnetic cluster size dependence of normalized noise and SNR at a recording density of 200 kfci. As expected, media noise and SNR are improved as the magnetic cluster size decreases, similar to the case of longitudinal media [7]. This result indicates that decreasing the magnetic cluster size is an effective means to increase bit density, leading to higher areal recording density.…”

“…Magnetic cluster size calculated from an MFM image is useful to analyze the origin of media noise [6], [7]. Manuscript In this study, we report on the characteristics of CoPtCr-SiO media with soft underlayers (SUL), especially focusing on the dependence of magnetic properties and read-write performance on magnetic cluster size.…”

Influence of inhomogeneous coercivities on media noise in granular perpendicular media investigated by using magnetic force microscopy

“…The noise data and signal-to-noise ratio (SNR) were extracted from the MFM image data of written bits by using a Fast Fourier Transformation (FFT) method [15,16], and the latter is defined as…”

“…Magnetic force microscopy (MFM) is a useful tool for measuring magnetic behaviors of microscopic areas in magnetic recording media [14]. There are generally two kinds of MFM measurement techniques: (i) ex situ measurement in the absence of external magnetic field, which is generally used for the observation of magnetization distribution and the associated analysis [15][16][17]; and (ii) in situ measurement in the presence of an external field either normal or parallel to film plane [18]. The latter is helpful for investigation in detail of the switching behavior in microscopic scale, for instance, observation of DC-erasure process in magnetic recording media [18].…”