Magnetic Fine Structure and High Resolution MFM Observation of Ultra High Density Magnetic Recording Media Aiming at Tera-bit/inch^2

1. 高密度磁性记录介质的磁性精细结构与记录介质噪声（1.1）介质噪声-矫顽力叠加法分析介质噪声与磁性的相关性采用磁力显微镜技术建立了介质噪声-矫顽力叠加法，并应用该方法研究了400 ~ 600 Gbit/inch^2级垂直介质的介质噪声来源。结果表明：(1)介质中磁化反转场的空间波动，波动长度约为100nm，(2)记录磁头的磁场梯度不足。（1.2）FePt纳米点状介质和纳米空穴介质的制备研究发现，Nb^+、Ga^+和Cr^+离子的离子辐照使L1_0FePt的矫顽力从10kOe降至接近0。然后用Ga^+ FIB成功制备了约100平方的磁性纳米点。采用氧化铝阳极氧化法制备了Co纳米孔介质。对两种介质进行了磁化反场分析。这两种媒体都具有超过1tb /inch^2.2的超高密度记录媒体的高潜力。原子~纳米空间分辨率磁成像方法的发展（2.1）高空间分辨率磁针尖的发展要实现小于10 nm的高分辨率，必须在磁针尖上溅射具有高饱和磁化强度和高矫顽力的磁性薄膜。研究了高分辨率MFM尖端的制备工艺。首先用等离子体氧化法对Si针尖表面进行氧化处理，然后在氧化后的针尖上溅射FePt。最后，在900K左右退火，获得了高分辨率的磁力显微镜尖端。（2.2）频率检测方法引入频率检测方法，提高MFM系统的分辨率。由于频率检测系统的不稳定性，目前还不能很好地工作。少

1. Magnetic fine structure and recording medium noise of high density magnetic recording media(1.1) Correlation analysis between medium noise and magnetic properties analyzed by the medium noise-coercivity overlapping methodMedium noise-coercivity overlapping method was developed by using magnetic force microscopy and was used to study the origin of medium noise of 400〜600 Gbit/inch^2 class perpendicular media. It was made clear that medium noise arises from (1) a spatial fluctuation of magnetization reversal filed in the media, where fluctuation length extends to about 100nm, (2) an insufficient magnetic filed gradient of recording head.(1.2) Fabrication of FePt nano-dot patterned media and nano-hole mediaIt was found that coercivity of L1_0FePt reduces by ion irradiation of Nb^+, Ga^+ and Cr^+ ions from 10kOe to almost 0. Then magnetic nano-dot with about 100 square was successfully fabricated by Ga^+ FIB. Co nano-hole medium was also fabricated by anodic oxidation of alumina. Magnet … More ization reversal filed analysis was done for both media. Both media have high potential for ultra high density recording media over 1 terabit/inch^2.2. Development of magnetic imaging method with atomic 〜 nano spatial resolution(2.1) Development of magnetic tip with high spatial resolution MFMMagnetic thin films with high saturation magnetization and high coercivity must be sputtered on to MFM tips to achieve high resolution less than 10 nm. The fabrication process to obtain such high resolution tip for MFM was studied. Firstly, surface of Si tip was oxidized by plasma oxidation, and then FePt was sputtered on the oxidized tip. Finally, by annealing around 900K, high resolution tip was obtained for magnetic force microscope. Spatial resolution was determined by Fourier analysis and was revealed to be 11-15 nm.(2.2) Introduction of frequency detection methodFrequency detection method was introduced to improve a resolution to MFM system. Frequency detection system did not work well so far due to instability. Less