Magnetic properties of small deposited 4d and 4f transition metal clusters

小型沉积 4d 和 4f 过渡金属团簇的磁性

• 批准号: 5455048
• 负责人: Professor Dr. Wilfried Wurth (†)
• 金额: --
• 依托单位: Institut für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5455048?language=en
• 关键词: Magnetic; properties; small; deposited; 4d

Small clusters are intriguing systems because their physical and chemical properties lie somewhere in between the properties of their atomic or molecular constituents and the respective bulk solids. For larger clusters specific physical quantities typically emerge as a smooth function of the size of the clusters. This evolution is often a result of the changes in the average coordination of the constituents as a function of cluster size. If the cluster size gets comparable to or smaller than the wavelength of the electrons which determine the physical properties we enter the regime where quantum size effects become important. In this size regime the evolution of physical quantities becomes less predictable and typically adding or removing a single atom or molecule from a cluster may result in very significant changes. However, small cluster have the advantage that they present tractable systems for sophisticated high-level theoretical treatments. Hence, small clusters are an ideal playground for the test of theoretical models against experimental results.The aim of the proposed project in the framework of the Schwerpunktprogramm is to study the size dependent magnetic properties of small supported metal clusters. We plan to investigate small 4d transition metal clusters (e.g. Mo, Ru, Rh, Pd) where the 4d electrons are delocalized and which show no magnetism in the bulk or as ultrathin thin films as well as 4f rare earth metal clusters (e.g. Gd) where the magnetic properties are governed by the localized, atomic like 4f electrons.The clusters will be size selected prior to deposition; cluster sizes will be in the range from 2 to 20 atoms. We will perform x-ray magnetic circular dichroism experiments (XMCD) in the soft X-ray regime using circular polarized synchrotron radiation. The goal is to study the size dependent magnetic structure of these clusters and in combination with theoretical studies to get detailed information of the magnetic coupling within the clusters and relative to the substrates. In particular, the XMCD studies will allow us to extract spin and orbital magnetic moments for the atoms in the clusters.

小团簇是一个有趣的系统，因为它们的物理和化学性质介于原子或分子组成的性质和各自的大固体之间。对于较大的星系团，特定的物理量通常作为星系团大小的平滑函数出现。这种演变通常是成分的平均配位随簇大小的函数变化的结果。如果团簇的大小与决定物理性质的电子的波长相当或更小，我们就进入了量子尺寸效应变得重要的区域。在这种大小范围内，物理量的演化变得更难预测，通常情况下，在团簇中添加或移除单个原子或分子可能会导致非常重大的变化。然而，小集群的优势在于，它们为复杂的高水平理论处理提供了易于处理的系统。因此，小团簇是检验理论模型和实验结果的理想场所。在Schwerpenkt计划框架下提出的项目的目的是研究小支撑金属团簇的尺寸依赖的磁性。我们计划研究小型4d过渡金属团簇(如Mo、Ru、Rh、Pd)和4f稀土金属团簇(如Gd)，其中4d电子是离域的，并且在块体或超薄膜中没有显示磁性。在4f稀土金属团簇(例如Gd)中，磁性由局域的类似原子的4f电子控制。我们将利用圆偏振同步辐射在软X射线区域进行X射线磁性圆二色实验(XMCD)。我们的目标是研究这些团簇的大小相关的磁结构，并结合理论研究来获得团簇内和相对于衬底的磁耦合的详细信息。特别是，XMCD研究将使我们能够提取团簇中原子的自旋和轨道磁矩。