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

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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