Dynamo magnetic domain analysis by nano-scale resolution MFM for high-density magnetic recording media

为了开发大于1Tbit/inch^2的超高密度磁记录介质，降低由于介质磁化强度的时空波动而产生的介质噪声是一个重要问题。因此，需要对磁畴结构进行高空间分辨率的动态分析。本研究采用原位磁力显微镜（MFM）在强磁场下进行研究，目的如下：(1)横向分辨率小于5nm的MFM系统的开发(2)利用MFM进行磁畴结构动态分析的开发(3)在高密度磁记录介质中的应用。1)采用L1_0有序FePt合金制备了10nm分辨率的高矫顽力MFM尖端（Hc>10kOe）。通过计算不同形状尖端的传递函数，阐明了分辨率小于5nm的高分辨率尖端的设计。圆柱形尖端的椭圆度为~ tan70°，是高分辨率MFM尖端的较好选择。这些尖端的制造正在进行中。2)开发了强磁场下的原位动态MFM测量方法，并将其应用于各种高密度磁记录介质，如合成蕨类磁介质、图纹介质等。揭示了Hc在介质中的纳米级分布。

To develop ultra-high density magnetic recording media more than 1Tbit/inch^2 the reduction of media noise, which was occurred by the spatial and temporal fluctuation of media magnetization is important problem. Therefore the dynamic analysis of magnetic domain structure with high spatial resolution will be needed. In the present study, the research was carried out by using in-situ magnetic force microscope (MFM) in strong magnetic fields for the following purpose.(1)the development of MFM system with lateral resolution less than 5 nm(2)the development of dynamic analysis of magnetic domain structure using MFM(3)application of to high density magnetic recording mediaThe following results are obtained.1)High coercivity MFM tips with 10nm resolution (Hc>10kOe) were fabricated by using L1_0 ordered FePt alloy. The design of high-resolution tips with less than 5nm resolution were clarified by calculating the transfer function of the tips with various shape. Cylindrical tips with an spheroidal tip-end having an ellipticity of〜tan70°was found to be better candidates of high resolution MFM tips. The fabrication of these tips is in progress.2)In-situ dynamic MFM measurements in strong magnetic field were developed and applied to various high-density magnetic recording media, such as synthetic fern-magnetic media, patterned media. The nano-scale Hc distribution in the media was revealed.