Fabrication of magnetic metal wires by using self-organization on stepped surfaces and its application to three dimensional super lattices

具有人工一维周期性的金属超晶格具有层间交换耦合、磁电阻和垂直磁各向异性等重要性质。巨磁阻效应实际上用于高密度磁记录系统的阅读头。然而，多层的方法仅限于制备一维周期性结构。本论文主要研究了磁性金属丝和磁性金属膜在磁性基底台阶边缘的生长，并对其结构和磁性进行了研究。此外，我们还研究了这种自组织过程用于形成和控制三维纳米结构的可能性。本研究的主要结果是结构控制和增强的FePt合金薄膜上生长的阶梯Pt底层的导电性。增强的双折射率是一个有用的效果，并解释了畴壁钉扎在台阶边缘。对于提高的双折射率，几何效应起着重要的作用，双折射率不仅取决于衬底的斜切角，而且还取决于衬底的斜切方向。对薄膜生长和自组织过程的基本认识也得到了一些结果。在Co/Ru体系中实现了单原子层控制，制备了人工反铁磁CoRu合金。用同样的方法成功地低温制备了L1_0有序FePt合金。

It is well known that metallic superlattices with artificial one-dimensional periodicity show important properties such as interlayer exchange coupling, magnetoresistance and perpendicular magnetic anisotropy. Giant magnetoresistnace is actually used for reading heads of high density magnetic recording systems. However, the method of multilayering is limited to preparation of one-dimensional periodic structures. It is hoped that a new method to fabricate artificial periodic structures, which could be applied for three-dimensional artificial nanostructures, is developed.In this study, we have studied structures and magnetic properties of magnetic metal wires and films grown at step edges of nonmagnetic underlayers. Additionally, we have investigated on possibility that such a self-organization process is utilized for forming and controlling three dimensional nanostructures. The main result of this study is structural control and enhanced coercivity in FePt alloy films grown on stepped Pt underlayers. The enhanced coercivity is an useful effect, and is explained by domain wall pinning at step edges. For the enhanced coercivity, geometrical effects play an significant role, and the coercivity depends not only on the miscut angle but also the miscut direction of substrates. Results for basic understandings of thin film growth and self-organization process are also obtained. Monatomic layer control is achieved in Co/Ru system, and artificial antiferromagnetic CoRu alloys are prepared. Low-temperature fabrication of L1_0-ordered FePt alloys is successfully performed by the same technique.