High Density Information Storage Materials Research using Laser Ablation Technique

本研究旨在探索用于高密度数据存储（包括磁记录和磁光记录）的贵金属材料。为此，将在良好控制条件下制备的记录介质的磁性、磁光和结构特性与记录性能联系起来是很重要的。本文提出了一种利用激光烧蚀技术开发新型加工系统的设想。研制成功了一种新型的Nd: YAG激光烧蚀系统。与市售系统相比，该系统具有独特的特点。首先，在沉积过程中可以旋转所选材料的靶材，从而可以连续改变膜的组成。因此，人们可以根据需要优化薄膜的磁性，从而获得高记录性能。由于靶材与衬底之间的距离较大，在2英寸以上的直径范围内，厚度和成分的均匀性优于5%。此外，还具备了磁光特性的原位测量能力。实验证明，该系统在制造条件下具有可控性和可重复性。实验主要针对sr -铁氧体薄膜和Co-Ag颗粒薄膜进行。结果可总结如下：1。sr -铁氧体薄膜在650 ~ 800℃退火2小时后，表现出较高的垂直磁各向异性（*10 6 erg/cc）。整体的磁性能对未来高密度垂直磁记录具有很大的应用前景。为了获得更好的磁性，需要进一步优化制造工艺。Co-Ag颗粒薄膜在含量为20at%左右时表现出较大的垂直磁各向异性。磁力显微镜对磁畴的观察支持这种高磁各向异性的存在。对其起源的了解甚少，有待进一步的详细研究。结果表明，所开发的激光沉积系统不仅可以用于数据存储应用，还可以用于其他器件的贵重材料的探索。少

The present research aims to investigate into noble materials for high density data storage (both magnetic and magneto-optical recordings). For this purpose, it is important to correlate magnetic, magneto-optical and structural properties with recording performance of recording media fabricated under well-controlled conditions. A proposal to develop a new fabrication system using a laser ablation method was made in the present study.A newly designed laser ablation system using a Nd : YAG laser (1W) has been successfully developed. This system has unique features as compared with commercially available ones. First of all, a target of materials of choice can be rotated during deposition so as to enable to change film composition continuously. Therefore, one can optimize film composition for magnetic properties as desired, leading to high recording performance. Because of a large distance between target and substrate, the uniformity in thickness and composition is better than 5% over 2" d … More iameter. Also, in-situ capability for measuring magneto-optical properties is equipped. The system has been proved to be controllable and reproducible for fabrication condition.The experiments were carried out mainly for Sr-Ferrite thin films and Co-Ag granular films.The results may be summarized as follows :1.Sr-Ferrite films exhibit high perpendicular magnetic anisotropy (*10 6 erg/cc) after annealed at 650-800C for 2 hrs. The over all magnetic properties are found to be very promising for future high density vertical magnetic recording. Further optimization for fabrication processes is needed for better magnetic behaviors.2.Co-Ag granular thin films exhibit a large perpendicular magnetic anisotropy when Cocontents are around 20at%. Observations of magnetic domains by magnetic force microscopy supports the existence of such a high magnetic anisotropy. Very little understanding of the origin is obtained, which remains for further detailed studies.3.The results demonstrated indicate that the laser deposition system developed is proved to capable for exploring noble materials for not only data storage applications but also other devices. Less