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

最近，在由磁层和非磁层交替组成的超晶格中观察到了巨磁电阻效应。由于超晶格巨磁电阻效应在高灵敏度磁阻磁头中的应用，超晶格的巨磁电阻效应备受关注。巨磁电阻效应对超晶格界面的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尚不清楚。本研究的目的是通过对薄膜形成过程的分子动力学模拟来阐明纳米尺度的界面结构及其与沉积参数之间的关系。1998年，为了阐明溅射工艺参数对Co/Cu超晶格结构的影响，我们对Co/Cu超晶格进行了分子动力学模拟。结果如下：1)在入射原子动能较低的情况下，对应的…此外，对于蒸发法，我们认为在岛状生长模式下，表面粗糙度的存在可能会导致针孔的形成，这可能是由于针孔破坏了Co层之间的反铁磁耦合而导致磁电阻比的低值。2)对于与离子束溅射方法相对应的入射原子动能较高的情况，在界面上观察到了互扩散。3)界面上的互扩散量强烈地依赖于入射角和原子的入射能量。在相同的原子入射能量下，随着原子入射角度的增加，表面的互扩散量减少。表面结构的模拟结果与以前报道的用沉积参数变化溅射法(溅射过程中改变Ar气压)在表面制备纳米结构的实验结果是一致的(A.Tsukamoto，et.Al，J.Magn.SoC。1996年第349卷))。分子动力学模拟有助于了解上述磁体的纳米结构。较少

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