Structure and magnetism of cluster ensembles on metal surfaces: Microscopic theory of the fundamental interactions

金属表面团簇系综的结构和磁性：基本相互作用的微观理论

• 批准号: 210162829
• 负责人: Professor Dr. Gustavo M. Pastor
• 金额: --
• 依托单位: Max-Planck-Institut für Mikrostrukturphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/210162829?language=en
• 关键词: Structure; magnetism; cluster; ensembles; metal

The structural and magnetic properties of interacting 3d transition-metal clusters on noble-metal surfaces are investigated by combining first-principles and model quantum theory. The substrate-mediated binding energies and magnetic couplings between clusters are determined in the framework of the Green’s functions Korringa-Kohn-Rostoker (GF-KKR) approach to density-functional theory (DFT). The effects of spin-orbit interactions and noncollinear magnetic order are determined in the framework of selfconsistent tight-binding theory. A systematic study is performed as a function of experimentally relevant parameters such as particle size N (e.g., FeN, CoN, and CrN), type of substrate (e.g., different Cu, Ag and Au surfaces), intercluster distance, relative orientation of the clusters (both structural and magnetic), and surface coverage. Special attention is paid to quantum electronic-structure effects, particularly in the small-size nonscalable regime. Simple effective cluster-interaction models are derived on the basis of the ab initio GFKKR calculations in order to determine the structural relaxation in the nanostructure. The fundamental magnetic properties of interacting clusters, such as the spin and orbital magnetic moments, possible complex noncollinear magnetic orders, and magnetic anisotropy energy are determined for the optimized geometries. The effects of interactions and relaxation on the magnetic properties are analyzed in detail. The results are compared with current experiments (e.g., STM, STS, MOKE and XMCD). The present combination of complementary theoretical tools aims to achieve a microscopic understanding of cluster interactions at surfaces and contribute to refine the design of new cluster materials with tailored magnetic properties.

结合第一性原理和模型量子理论研究了贵金属表面三维过渡金属团簇的结构和磁性。基质介导的结合能和团簇之间的磁耦合是在格林函数的框架下确定的，Korringa-Kohn-Rostoker （GF-KKR）方法的密度泛函理论（DFT）。在自洽紧密结合理论的框架下，确定了自旋轨道相互作用和非共线磁序的影响。系统的研究是作为实验相关参数的函数进行的，如粒度N（例如，FeN， CoN和CrN），衬底类型（例如，不同的Cu， Ag和Au表面），簇间距离，簇的相对方向（结构和磁性）以及表面覆盖率。特别关注量子电子结构效应，特别是在小尺寸不可伸缩的状态下。为了确定纳米结构中的结构弛豫，在从头计算GFKKR的基础上推导了简单的有效簇-相互作用模型。确定了相互作用团簇的基本磁性，如自旋和轨道磁矩、可能的复杂非线性磁序和磁各向异性能。详细分析了相互作用和弛豫对磁性能的影响。结果与现有实验（如STM、STS、MOKE和XMCD）进行了比较。目前的互补理论工具的组合旨在实现对表面团簇相互作用的微观理解，并有助于改进具有定制磁性的新团簇材料的设计。