Magnetic reversal field map combined with medium noise analysis in CoCrPt–SiO2 granular perpendicular recording medium

Abstract

Reverse dc erase medium noise analysis on exchange-coupling effect in coupled granular/continuous perpendicular recording media J. Appl. Phys. 93, 7855 (2003); 10.1063/1.1557757 Effects of intermediate layers on magnetic properties and read/write performance in CoCrPt perpendicular recording media with an FeHfN soft magnetic underlayerThe spatial distribution of the magnetic reversal field ͑MRF͒ in a CoCrPt-SiO 2 granular perpendicular recording medium was measured with in-field magnetic force microscopy and combined with the recorded pattern and the medium noise observed at the same location. The areas having low MRF tend to make reverse domains at bit or zigzag transition boundaries, while regions with high MRF do not correlate well with medium noise. The MRF map measured at 20 Oe intervals shows that magnetic reversal occurs mainly in regions adjacent to an already reversed area, suggesting the existence of moderate intergrain exchange couplings. It is concluded that control of the spatial fluctuation of physical parameters such as intergrain exchange interactions, the anisotropy field, grain size, and chemical composition is essential to reduce the medium noise.

Photo excited scanning probe microscopy for buried nano structure analyses

“…This result indicates that Etotal is constant for given A. In the X-EFM experiment, since the V b = 0 V, E 101 a1 should be balanced with L1 V Zp• This balance can be expressed as (3) Therefore, A can be estimated to be 2s 0 L1 V 2 p/z. On the other hand, we experimentally obtained L1 V 2 P of 2.6 eV as shown in figure 3.…”

“…Scanning probe microscopy (SPM) has been widely used for observation of surface with atomic resolution. Surface topography and various physical properties such as electric potential [1,2] and magnetic orientation [3] of nanometer domains can be evaluated with SPM systems. On the other hand, chemical properties such as elements distribution and bonding states of elements cannot be dealt with by using any SPM system without difficulty.…”

A novel analysis method for noise of perpendicular recording media

“…The MFM can simultaneously provide information about the topography and the magnetization process with a high resolution. To understand the in situ magnetization reversal behaviour, our group has constructed an in-field MFM system and reported the magnetic reversal field (H R ) map technology that can reveal the spatial fluctuation of the H R in media [10][11][12]. The H R -map can directly show us the distribution of the magnetization reversal field.…”

Tuning the properties of magnetic thin films by interaction with periodic nanostructures

“…A single magnetic bit is stored on the hard disk by magnetizing a small region consisting of several tens of magnetic grains with parallel magnetization either pointing up- or downwards. Increasing areal densities of recording bits, while maintaining the signal-to-noise ratio, demands a reduction of the grain size [1]. As a result of the miniaturization, however, the grain size approaches the superparamagnetic limit, below which stored information is lost due to thermal fluctuations of the magnetization.…”