Electron Pairing and Spin Dynamics in Metal Clusters at Low Temperatures in a Molecular Beam

低温分子束中金属团簇的电子配对和自旋动力学

• 批准号: 0307782
• 负责人: Walter De Heer
• 金额: $ 36万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-15 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0307782&HistoricalAwards=false
• 关键词: Electron; Pairing; Spin; Dynamics; Metal

Cluster physics approaches matter from the standpoint that material properties evolve systematically when clusters are increased in size one atom at a time until the bulk limit is reached. This approach has yielded important new insights into the physical properties of simple metal cluster systems. This individual investigator award supports a project addressing two fundamental problems: the physics of adiabatic spin-relaxation processes in ferromagnetic cluster systems and pairing correlations in paramagnetic cluster systems. (1) Adiabatic spin-relaxation processes, probed using molecular beam deflection methods, have been observed in all ferromagnetic cluster systems studied yet there the mechanism that mediates this process is unknown. (2) Cluster beam deflections at low temperatures reveal large even-odd oscillations in the electric dipole polarizabilities of niobium clusters, which are accompanied by exceptionally large permanent electric dipole moments. This indicates a symmetry-broken ground low temperature phase with strong electron-paring correlations, suggesting nascent superconductivity. Cluster beam investigations of these effects will have far-reaching consequences in the understanding of electronic correlations and spin dynamics in small systems. Graduate students involved in the project receive training in fundamental experimental techniques with cutting edge technology. This training will prepare them for a range of careers in academe, industry or government. The project is jointly supported by the Divisions of Materials Research (Condensed Matter Physics) and Physics (Atomic, Molecular, and Optical Physics).Cluster physics approaches matter from the standpoint that material properties evolve systematically when clusters of atoms are increased in size one atom at a time until the bulk limit is reached. It is important to explore at what size a piece of material becomes small enough that it looses its "normal," bulk behavior. In addition by studying clusters which are small enough not have behave like the bulk material, one may discover novel interesting phenomena. The state of the art molecular beam methods developed for this project are ideally suited to probe these extremely small clusters: clusters of virtually any metal can be produced at temperatures from 10 K to 300 K in a new ultra-low temperature pulsed-laser cluster-source. This project will investigate the magnetic and electric properties of very small clusters of metal atoms. At low temperatures, the electric charge spontaneously separates in niobium, vanadium and tantalum clusters. This may suggest nascent superconductivity. Investigations of these effects are proposed and they will have far-reaching implications in the understanding superconductivity and related electronic effects in these important materials. Graduate students involved in the project receive training in fundamental experimental techniques with cutting edge technology. This training will prepare them for a range of careers in academe, industry or government. The project is jointly supported by the Divisions of Materials Research (Condensed Matter Physics) and Physics (Atomic, Molecular, and Optical Physics).

团簇物理学的观点是，当团簇的大小一次一个原子地增加，直到达到体积极限时，材料性质会系统地演变。这种方法产生了重要的新的见解简单的金属簇系统的物理性质。这个个人研究者奖支持一个解决两个基本问题的项目：铁磁簇系统中绝热自旋弛豫过程的物理学和顺磁簇系统中的配对相关性。(1)绝热自旋弛豫过程，探测使用分子束偏转方法，已被观察到在所有铁磁簇系统的研究，但有介导这一过程的机制是未知的。(2)团簇束偏转在低温下揭示大的偶奇振荡的铌团簇的电偶极子极化率，这是伴随着异常大的永久电偶极矩。这表明了一个具有强电子配对相关性的低温相，表明了新生的超导性。团簇束研究这些影响将有深远的影响，在理解电子相关性和小系统的自旋动力学。 参与该项目的研究生将接受尖端技术的基本实验技术培训。这项培训将为他们在企业，工业或政府的一系列职业生涯做好准备。 该项目由材料研究部（凝聚态物理学）和物理学部（原子、分子和光学物理学）共同支持。团簇物理学从原子团簇的大小一次一个原子地增加直到达到体积极限时材料性质系统地演变的观点出发来研究物质。重要的是要探索一块材料在多大的尺寸下变得足够小，以至于它失去了“正常”的整体行为。 此外，通过研究足够小而不像大块物质那样行为的团簇，人们可能会发现新的有趣现象。 为该项目开发的最先进的分子束方法非常适合探测这些极小的团簇：在新的超低温脉冲激光团簇源中，几乎任何金属的团簇都可以在10 K至300 K的温度下产生。这个项目将研究非常小的金属原子团簇的磁性和电学性质。在低温下，电荷自发地分离成铌、钒和钽簇。 这可能暗示着新生的超导性。这些影响的调查建议，他们将有深远的影响，在理解这些重要材料的超导性和相关的电子效应。 参与该项目的研究生将接受尖端技术的基本实验技术培训。这项培训将为他们在企业，工业或政府的一系列职业生涯做好准备。该项目由材料研究（凝聚态物理）和物理（原子，分子和光学物理）部门共同支持。