Research of the nano-structure of magnets by molecular dynamics simulation and deposition parameter variation sputtering method

最近，在由磁性层和非磁性层交替组成的超晶格中观察到巨磁电阻（GMR）效应。超晶格巨磁电阻效应因其在高灵敏度磁电阻磁头中的应用而受到广泛关注。巨磁电阻效应对超晶格界面结构和沉积参数非常敏感，但巨磁电阻效应与界面结构之间的关系还不清楚，本研究的目的是通过对薄膜形成过程的分子动力学模拟，阐明纳米尺度下的界面结构及其与沉积参数之间的关系，1998年，摘要为了阐明溅射沉积参数对Co/Cu超晶格结构的影响，对Co/Cu超晶格进行了分子动力学模拟。结果如下：1）对于入射原子动能较低的情况，对应 关于我们 对于蒸发法，这可能是由于在岛状生长模式下表面粗糙度的存在而导致针孔的形成，针孔的形成破坏了Co层间的反铁磁耦合，从而导致磁阻比的降低。2）对于离子束溅射法入射原子动能较高的情况，界面处的互扩散量强烈地依赖于入射角和原子的入射能量。在原子入射能量相同的情况下，表面互扩散量随原子入射角的增大而减小，表面结构的模拟结果与文献报道的用变参数溅射法（溅射过程中改变Ar气压）在表面制备纳米结构的实验结果（A.Tsukamoto，et.等人，J. Magn. Soc. Jpn.，Vol.20.114（1996）349.）。分子动力学模拟有助于了解上述磁体的纳米结构。少

Recently, a giant magnetoresistance (GMR) effect was observed in superlattices comprised of alternating magnetic and nonmagnetic layers. Much attention has been devoted to the GMR of superlattices because of the application for high sensitive magnetoresistive heads. The GMR effect is very sensitive to the structure atthe interface of superlattices and the deposition parameter, however, the relationships between GMR and interface structure is still not clear.The purpose of this research is clarifying the structure of the interface at the nanoscopic scale and relationships between those structure and deposition parameter by using molecular dynamics simulations of film formation process.In 1998, for the purpose of clarifying the effect of the deposition parameters in sputtering on the structure of Co/Cu super lattices, molecular dynamics simulations have been performed for Co/Cu super lattices. The results as follows :1)For the case of low kinetic energies of incident atoms corresponding … More to evaporation method, it is suggested that the formation of pinholes might been caused because of the existence of roughness at surface in island growth mode.This may cause the low values of the magnetoresistance ratio because that the pinholes broken the anti-ferromagnetic coupling between Co layers.2)For the case of high kinetic energies of incident atoms corresponding to Ion-beam sputtering method, the interdiffusion at the interface is observed.3)The amount of interdiffusion at the interface strongly depend on the angle of incidence and the incident energy of atoms. At same incident energy of atoms, the amount of interdiffusion at the surface decrease with increasing the angle of incidence of atoms.The simulated results of the structure at the surface is good agreement with the previously reported experimental results of fabrication of nano-structure at surface by deposition parameter variation sputtering method (Ar gas pressure was varied during sputtering) (A.Tsukamoto, et. al, J.Magn. Soc. Jpn., Vol. 20.114 (1996) 349.). The molecular dynamics simulation is useful to know the nano-structure of magnets as mentioned above. Less