Four-Dimensional Probe of Electron Spin-Spin Coupling

本项目提供了对两个电子自旋之间的相互作用能量的新认识，并通过自制的显微镜精确控制它们之间的距离，该显微镜能够分辨小于人类头发宽度的百万分之一的尺寸。定量数据构成了理解磁有序的基础，并提供了可用于分析广泛磁现象的数值结果（而不是参数）。实验与理论相结合的研究将影响基于新材料的电子自旋特性的下一代信息存储设备和未来技术。该显微镜提供了两个自旋之间空间依赖相互作用的图像，并允许直接可视化这种相互作用。使用自制仪器进行测量，获得以前不可能获得的新认识，为学生提供了有价值的教育和训练。这个项目教会学生如何解决难题，并赋予他们技能，使他们能够在未来的职业生涯中解决看似无关但极具挑战性的问题。这项研究的副产品有助于在一个技术日益复杂的社会中创造一支高技能的劳动力队伍。技术摘要：电子自旋之间的耦合是理解磁现象的核心，也是原子、分子和凝聚态物质中许多重要效应的基础。对于具有自旋矩的原子和分子吸附在固体表面并与附近的自旋相互作用，耦合能量取决于交换相互作用和磁各向异性。利用扫描隧道显微镜（STM），在0.6 K和高达9特斯拉的磁场下，通过将具有电子自旋的分子附着在针尖上，测量吸附在表面的单个磁性原子或分子在不同位置（x,y,z）上的耦合能(E)，可以在四个维度（E,x,y,z）上探测电子自旋耦合。自旋尖端的实现需要实现一种基于单原子和分子的STM操纵的新型合成方法。这个项目产生了精确的数据，可以通过理论计算进行定量分析。这种实验和理论之间的协同作用使理论框架在以前无法达到的水平上得到验证，并进一步将该项目扩展到新的和不可预见的方向。然而，自旋-自旋相互作用的空间依赖性的结果也可能偏离传统的期望，因此需要一个新的思维框架。

Non-Technical AbstractThis project provides new understanding into the interaction energy between two electron spins with precise control of the distance between them by a homemade microscope capable of resolving dimensions below a millionth of the width of a human hair. The quantitative data form the basis for understanding magnetic ordering and provide numerical results that can be used (instead of parameters) in the analysis of a broad range of magnetic phenomena. The combined experimental and theoretical research impacts the next generation of information storage devices and futuristic technologies based on the electron spin properties of new materials. This microscope provides images of the spatially dependent interaction between two spins and allows direct visualization of this interaction. The use of homemade instrument to make measurements previously not possible to gain new understanding provides valuable education and training of students. This project teaches the students how to solve difficult problems and endows them with skills that allow them to tackle seemingly unrelated and highly challenging problems in their future careers. A byproduct of this research contributes to the creation of a highly skilled workforce in a society with increasingly sophisticated technologies. Technical AbstractThe coupling between electron spins is central to the understanding of magnetic phenomena and forms the basis for a number of important effects in atoms, molecules, and condensed matter. For atoms and molecules with spin moments adsorbed on a solid surface and interacting with a nearby spin, the energy of coupling depends on the exchange interaction and the magnetic anisotropy. The electron spin-spin coupling can be probed in four dimensions (E,x,y,z) using the scanning tunneling microscope (STM), at 0.6 K and up to 9 Tesla magnetic field, by attaching a molecule with an electron spin to the tip and measure the coupling energy (E) at different locations (x,y,z) over a single magnetic atom or molecule adsorbed on the surface. The realization of the spin-tip requires the implementation of a novel synthetic method based on STM manipulation of single atoms and molecules. This project yields precise data that enable quantitative analysis by theoretical calculations. This synergy between experiment and theory leads to the validation of the theoretical framework in understanding magnetism at a level not previously attainable and further extends this project to new and unforeseen directions. Still, results of the spatial dependence of the spin-spin interaction may also deviate from the conventional expectation and thus require a new framework of thinking.