有序表面合金对磁性薄膜的生长及磁性调控的计算研究

A wide range of intriguing magnetic phenomena that are of fundamental interest and technological importance can occur in magnetic films when their thicknesses approach nanometer scale. Ultrathin films have attracted significant attention particularly because their magnetic properties can be strongly influenced by the interaction with the supporting substrate. This can occur, for example, through elastic strain, interface anisotropy, or because of the stabilization of unique film structures that do not occur in bulk form. In the proposed research project, we will investigate the growth and magnetic properties of ultrathin Fe films on ordered surface alloys. Practical interest in surface alloys as new materials has been motivated by the fact that their properties can differ substantially from the bulk surfaces of their constituent elements, with attention given overwhelmingly to chemisorption and catalytic behavior in the past. This outlook is encouraged by the prospect of tailoring properties through a careful selection of alloy constituents. Among the numerous surface alloy systems that are known, our investigations will concentrate on the surface-confined c(2×2) ordered alloys that are formed by various noble metals (Cu, Ag, Au, Pt, Pd) on W(100) and Mo(100) refractory metal surfaces. Relevant aspects of electronic structure that affect interface anisotropy through hybridization of electronic states at the interface, namely d-bands at the Fermi level, differ significantly between the noble and refractory metals, and to some extent within the different groups. Therefore, by concentrating on this class of surface alloys, it should be possible to vary interface anisotropy controllably by systematically changing the alloying element and substrate matrix, without otherwise changing other important factors such as elastic strain. These investigations will be carried out using first-principles calculations and Monte Carlo simulations combined with experiment in close collaboration. This research will allow us to evaluate empirically the degree to which interface anisotropy can be varied using surface alloy substrates and may lead to a practical method for exercising control over the magnetic properties of ultrathin films.

超薄磁膜具有巨电导、巨磁电阻效应、巨霍尔效应等许多独特的性能，对其生长和性质的研究具有重要的科学意义和实用价值。磁性薄膜在衬底上生长时，不同的衬底导致不同的晶格失配应变，界面磁各向异性，甚至产生体材料中不可能存在的独特薄膜结构。本项目拟通过第一性原理计算和蒙特卡洛模拟，系统地研究Fe超薄磁性膜在有序表面合金衬底上的生成机理和磁性质。从微观上理解磁性薄膜与有序表面合金的界面结构，薄膜在有序表面合金衬底上的热力学稳定性及形成的动力学过程，为实验制备提供可靠的理论指导。通过对其磁学性质如磁矩、交换作用常数、居里温度、磁晶各向异性及其对电场的响应等的计算，深入探讨利用表面合金衬底实现对薄膜磁性的调控，为设计具有应用价值的新型磁性薄膜奠定理论基础。

超薄磁膜具有巨电导、巨磁电阻效应、巨霍尔效应等许多独特的性能，对其生长和性质的研究具有重要的科学意义和实用价值。磁性薄膜在衬底上生长时，不同的衬底导致不同的晶格失配应变，界面磁各向异性，甚至产生体材料中不可能存在的独特薄膜结构。本项目通过第一性原理计算和蒙特卡洛模拟，系统地研究Fe超薄磁性膜在有序表面合金衬底上的生成机理和磁性质。从微观上理解磁性薄膜与有序表面合金的界面结构，薄膜在有序表面合金衬底上的热力学稳定性及形成的动力学过程，为实验制备提供可靠的理论指导。通过对其磁学性质如磁矩、交换作用常数、居里温度、磁晶各向异性及其对电场的响应等的计算，深入探讨利用表面合金衬底实现对薄膜磁性的调控，为设计具有应用价值的新型磁性薄膜奠定理论基础。 在本项目的资助下，我们已发表学术论文20篇，全部为SCI收录；培养博士研究生2名；资助6人次参加国内国际学术会议；