Research on ferrite thin film with isolated small and pillar like structure for high density HDD medium

即使垂直磁记录系统现在已经上市，在硬盘驱动器（HDD）系统中的高密度记录仍然是关键问题。下一代的记录介质必须是离散型或图案化介质型，以获得大于每平方英寸1太比特的超高记录密度。磁性颗粒必须很小，以减少介质噪声。此外，谷物必须被隔离。本研究尝试采用纳米点晶化法制备钡铁氧体纳米点阵薄膜。室温下沉积的Ba-Fe-O薄膜为非晶态，无磁化。沉积在硅片上的Ba-Fe-O薄膜在700 ℃左右可以晶化并显示出磁性。为了降低钡铁氧体薄膜的晶化温度，本研究对几种底层材料进行了研究。结果表明，Pd-Pt混合合金底层适合于降低衬底温度， ...更多信息 非常小的粒子。还研究了Al膜作为非晶钡铁氧体薄膜的底层。Al底层上的非晶Ba-Fe-O层在650 ℃左右可以晶化。这比硅底层的温度低50 ℃。Al-Si合金是一种分相材料，在硅基体中形成了纳米级的Al斑点。尝试用铝硅底层制备纳米点状结构的钡铁氧体。在250 ℃的衬底温度下，通过相分离可以形成自组装的Al纳米点阵列。然后在室温下淀积非晶态Ba-Fe-O薄膜，淀积后在650 ℃下退火。测量的磁化强度对应于Al含量。这意味着，铝斑上的钡铁氧体层只能晶化，而硅基体上的其他部分仍然是非晶的，没有磁化。由于分辨率的限制，目前还不能确定是否制备出了纳米点状钡铁氧体薄膜。Δ M图显示磁性颗粒被分离，交换耦合被削弱。总之，利用自组装Al-Si底层制备图案化介质的新技术。少

High density recording in hard disk drive(HDD) system is still key issue even though a perpendicular magnetic recording system is now on the market. The recording medium for a next generation must be discrete type or patterned media type to attain an ultra high recording density greater than one tera bits per square inch. The magnetic grains must be small to reduce the media noise. Furthermore, the grains must be isolated. In this study, nano-spot crystallization for barium ferrite thin film has been tried to prepare the nano-spot array film of barium ferrite. The Ba-Fe-O films deposited at room temperature is amorphous and has no magnetization. The Ba-Fe-O films deposited on silicon wafer can be crystallized at around 700 C and show magnetic properties. In this study to lower the crystallization temperature for barium ferrite thin film, several kind of under layer materials were examined. As a results Pd-Pt mixed alloy underlayer is suitable for lowering the substrate temperature and … More very small particle. The Al film was also examined as an under layer for amorphous barium ferrite thin film. The amorphous Ba-Fe-O layer on Al under layer can be crystallized at around 650 C. This is 50 C lower than that for silicon under layer. It is know that Al-Si alloy is a phase separate material and nano-sized Al spots are synthesized in silicon matrix. It was tried to prepare barium ferrite with nano-spot like structure using Al-Si under layer. A self assembled nano dots array of Al can be created by phase separation at the substrate temperature of 250 C. Then ampourphous Ba-Fe-O films were deposited at room temperature and post-deposition annealed at 650 C. The measured magnetization is corresponding to Al content. This means that barium ferrite layer on Al spot can only be crystallized and other parts, which are on silicon matrix, are still amorphous and no magnetization. Due to the resolution limits, it is not yet confirmed that nano spot barium ferrite film was prepared. The delta M plots show that the magnetic grains are separated and exchange coupling is weakened. In conclusion, new technique to prepare a patterned medium using self assembled Al-Si under layer. Less