Magnetism, Electronic Structure, and Dynamics in Atomic Clusters

这个实验研究项目使用小的原子簇来研究分子特性之外的几个体特征和现象的发展——磁性、结构缺陷和相变。它的主要研究方向是铁和铁磁性粒子的磁有序以及盐体系中的超快离子和电子动力学。磁分量试图解决低维系统自旋有序中的许多理论不确定性。在一维和二维系统中，已经预测到铁磁有序增强，甚至居里温度升高，而表面原子占很大比例的小粒子被证明是研究此类效应的绝佳实验室。自旋倾斜和铁磁和反铁磁有序之间的竞争也在理论上进行了检验，并将在本工作中进行研究。动力学部分考察了卤化物团与光的相互作用，考察了各种能量（热、电子、振动和旋转）在加热、冷却、熔化和蒸发等有限系统中的作用。参与这项研究的研究生将接受培训，为他们在快速发展的光学科学、工程和纳米技术领域的工业、学术或政府工作做好准备，特别是在磁性和非易失性电荷存储器和光学计算等新兴领域。这项研究使用小的原子集合来检验单个原子和分子科学与整体物质科学之间的联系。特别是，它研究体磁性是如何从组成体物质的单个原子的磁性中产生的，以及小分子中温度、熔化和蒸发与各种动态现象的关系。这两个实验项目都涉及真空中的微小粒子束，以便这些粒子在完全隔离的原始状态下进行研究。因此，它们非常适合解决许多基本问题，包括材料中的磁性原子如何在更大的系统中保持或取消它们的磁性，光能如何加热小系统，以及一个粒子必须多大才能表现出诸如温度，晶体结构和材料相变化等整体特性和现象。这项研究与现代磁性和电子存储系统以及光存储和通信有着密切的联系。这个研究项目的学生在凝聚态、原子、分子和光学物理方面接受严格的训练，为工业或学术科学的职业生涯做好了充分的准备。

This experimental research project uses small clusters of atoms to examine the development of several bulk characteristics and phenomena-magnetism, structural defects, and phase transitions-out of molecular properties. Its main thrusts are in magnetic ordering in ferro- and ferri-magnetic particles and in ultrafast ion and electron dynamics in salt systems. The magnetic component seeks to address numerous theoretical uncertainties in the spin ordering of low-dimensional systems. Predictions of enhanced ferromagnetic ordering and even elevated Curie temperatures have been predicted in one- and two-dimensional systems, and small particles, with their large fraction of surface atoms, are proving to be an excellent laboratory in which to study such effects. Spin-canting and a competition between ferro- and antiferromagnetic orderings have also been examined theoretically and will be studied in this work. The dynamics portion examines the interactions of alkali-halide clusters with light, looking at the roles of various energies-thermal, electronic, vibrational, and rotational-in the finite-system equivalents of heating, cooling, melting, and evaporating. Graduate students participating in this research will receive training that will prepare them for industrial, academic, or government careers in the rapidly developing fields of optical science and engineering and nanotechnology, particularly the emerging fields of magnetic and non-volatile charge-based memory and optical computing.This research uses small collections of atoms to examine connections between the science of individual atoms and molecules and the science of bulk matter. In particular, it studies how bulk magnetic properties emerge from those of the individual atoms that comprise bulk matter and how temperature, melting, and evaporation are related to various dynamic phenomena in small molecules. Both experimental programs involve beams of tiny particles in vacuum, so that those particles are studied in the pristine state of perfect isolation. They are therefore well-suited to address many fundamental questions, including how the magnetic atoms in a material order themselves to retain or cancel their magnetism in larger system, how light energy heats small systems, and how large a particle has to be in order to exhibit such bulk properties and phenomena as temperature, crystal structure, and changes of material phase. This research has close connections with modern magnetic and electronic memory systems and with optical storage and communications. Students in this research program undergo rigorous training in condensed matter, atomic, molecular, and optical physics and are well prepared for careers in industrial or academic science.