Study of Ultra-High Debnsity Information Storage Materials

The present project is concerned with materials science of high density data storageespecially magnetic and magneto-optical recordings. The work is jointly collaborated with The groupStanford University in the USA.For furuter high density recording the controllability ofnanoscale structure in a recording medium is essential. Also，further development of novel materials with high magnetic an isotropy must be made. The present work已forcused on the above issues. the followings may be summarized as the results.1. orderedCo - D23 D2Pt alloy thin film is found to exhibit very high magnetic anisotropy 3x10 - D17 - D1 erg/ccat room temperature. This finding is the first to be reported.2. An ordered Co - D23 - D2Pt alloythin film is found to exhibit very high magnetic anisotropy 3 ×10 D17 D1 erg/cc at roomtemperature. This finding is the first to be reported.3. the thermal stability of magnetic recordingmedia CoCrPtTa strongly depends on activation volume. The activation volume is dependent onmagnetic field. decreasing with filed and then increases at fields beyond coercivity. This resultimplies that the dispersion of magnetic anisotropy of grains is predominant.4. the noise ofrecording performance of the above media increases with activation on volume.5. the field dependenceamorphous TbFeCo films which are being used for magneto-optical recording is very much differentfrom that for magnetic recording media. This implies that the thermal relaxation mechanism in thermal relaxation mechanismamorphous films is governed by a single energy potential value，as compared to the case of magnetic recording media。

The present project is concerned with materials science of high density data storage, especially magnetic and magneto-optical recordings. The work is jointly collaborated with the group of Stanford University in the USA.For furuter high density recording the controllability of nanoscale structure in a recording medium is essential. Also, further development of novel materials with high magnetic an isotropy must be made. The present work is forcused on the above issues. The followings may be summarized as the results.1. An ordered CoィイD23ィエD2Pt alloy thin film is found to exhibit very high magnetic anisotropy 3x10ィイD17ィエD1 erg/cc at room temperature. This finding is the first to be reported.2. An ordered CoィイD23ィエD2Pt alloy thin film is found to exhibit very high magnetic anisotropy 3 ×10ィイD17ィエD1 erg/cc at room temperature. This finding is the first to be reported.3. The thermal stability of magnetic recording media CoCrPtTa strongly depends on activation volume. The activation volume is dependent on magnetic field. decreasing with filed and then increases at fields beyond coercivity. This result implies that the dispersion of magnetic anisotropy of grains is predominant.4. The noise of recording performance of the above media increases with activation on volume.5. The field dependence of amorphous TbFeCo films which are being used for magneto-optical recording is very much different from that for magnetic recording media. This implies that the thermal relaxation mechanism in amorphous films is governed by a single energy potential value, as compared to the case of magnetic recording media.