Magnetic, Electronic, and Structural Development in Atomic Clusters

9731592布卢姆菲尔德 该研究项目研究孤立原子团簇中的磁性和电子结构，目的是将目前对原子和分子的理解与对大块材料的理解联系起来。 由于它们的低维度，集群提供洞察表面效应，量子尺寸效应，热弛豫过程，以及结构和电子相变的分子起源。 在这个计划中，团簇是在基于激光的源和分子束技术研究。 磁结构探测使用Stern-Gerlach 束偏转 方法 和 效果 作为 研究了表面增强磁化强度、表面和形状感生磁各向异性以及局域磁矩系统中的自旋倾斜。 该程序还搜索通常非磁性元素和合金的其他磁性有序簇。 用阴离子光剥离光谱研究了团簇的电子结构。 这项工作着眼于集群的大小，成分，形状和温度对（1）这些系统中的电子调节模式，（2）它们的结构和电子相，以及（3）它们的电子激发态的影响。 %这个研究项目研究仅比原子本身稍大的材料粒子的磁性和电子特性，作为弥合固体和分子之间理解上的差距的一种方式。 随着电子元件和磁存储系统变得越来越小，它们的尺寸不再能被简单地视为更大物体的小版本。 相反，这些微小的设备必须部分地被视为复杂的分子系统，具有量子力学，热波动和表面结构改变的复杂性 他们的行为 通过研究原子团簇中的磁性，该研究计划正在学习固体中的磁性如何从分子结构中发展出来，并绘制出最终产生磁存储介质的可能性。在其关于团簇电子和空间结构的工作中，该计划正在探索原子尺度附近的绝缘体和金属世界，并正在研究它们变得如此之小以至于几乎所有原子都在其表面时的行为。 ***

9731592 Bloomfield This research program examines magnetic and electronic structure in isolated atomic clusters, with the goal of connecting present understandings of atoms and molecules to those of bulk materials. Because of their low dimensionalities, clusters provide insight into surface effects, quantum size effects, thermal relaxation processes, and the molecular origins of structural and electronic phase transitions. In this program, clusters are prepared in laser-based sources and studied with molecular beam techniques. Magnetic structure is probed using the Stern-Gerlach beam deflection method and effects such as surface-enhanced magnetization, surface and shape induced magnetic anisotropy, and spin-canting in local moment systems are studied. This program also searches for additional magnetically ordered clusters of normally non-magnetic elements and alloys. Cluster electronic structure is studied by anion photodetachment spectroscopy. This work looks at the effects of cluster size, composition, shape, and temperature on (1) the modes of electron accommodation in these systems, (2) their structural and electronic phases, and (3) their electronically excited states. %%% This research program examines the magnetic and electronic properties of material particles only slightly larger than atoms themselves, as a way to bridge the gap in understanding between solids and molecules. As electronic components and magnetic memory systems become smaller, they reach sizes at which they can no longer be treated simply as small versions of larger objects. Instead, these tiny devices must be viewed in part as elaborate molecular systems, with the complexities of quantum mechanics, thermal fluctuations, and surface structure altering their behavior. By studying magnetism in clusters of atoms, this research program is learning how magnetism in solids develops from molecular st ructure and is mapping out possibilities for the ultimate generation of magnetic storage media. In its work on electronic and spatial structure in clusters, this program is exploring the world of insulators and metals near the atomic scale and is examining their behaviors when they become so small that nearly all their atoms are on their surfaces. ***