Understanding Electronic and Spin Structure at Organic / Metal Interfaces: Surfaces and Symmetry

随着电子技术在更小的设备中产生更大的存储器和处理能力，研究越来越多地关注分子作为电子电路的构建块。 由金属和半导体材料制成的更大的传统电路元件不仅要传导和存储电荷，还要传导和存储磁信息。 电子带有负电荷，这使得它们在移动时能够导电。 电子也像磁铁一样，因为它们具有一种称为“自旋”的性质。 如果革命性的基于分子的电子学要成为现实，我们必须能够理解和控制电荷和自旋如何不仅通过单个分子，而且在分子和其他材料（电路的其他部分）之间流动。在这个项目中，由化学系的化学结构，动力学和机制-A（CSDM-A）计划资助，亚利桑那大学的奥利弗蒙蒂教授和他的学生正在研究电荷和自旋如何在接触点与其他材料流动。 他们正在研究金属表面上的分子，以及金属表面上已被其他分子修饰的分子，以改变接触条件。 蒙蒂研究小组使用激光技术和扫描隧道显微镜（STM）的组合，可以成像单个原子和分子。 该研究旨在发现决定分子电子元件中电荷流和自旋流的重要分子结构因素。 研究生接受高等化学，光学物理和原子显微镜的培训和经验。 这项培训预计将为量子信息科学革命做好准备。 除了博士生的正式培训外，Monti教授还为亚利桑那大学的本科生退伍军人开发了一个项目，以获得研究经验和个性化的指导，从而在科学和工程领域取得成功。该项目的重点是定制有机半导体/金属界面的界面电子结构和电荷转移动力学。研究需要使用Ag在Cu（111）上的外延层来定制表面电子结构，以改变表面电子波长、表面电子密度和表面对称性。使用低温扫描隧道显微镜和稳态和时间分辨光电子能谱的组合，这些系统的变化对表面过程的影响进行检查。 因此，过程，如分子自组装，界面电子结构和电荷转移动力学的特点是在广泛的表面电子性质，而不改变界面的化学性质。 表面改性也在开发中，以促进Rashba分裂，而无需外部磁场。 这项研究涉及的吸附有机半导体，支持大电偶极子或可以诱导轨道混合的界面。如果实现这种类型的Rashba分裂，它可能对有机/金属界面的自旋态的控制和操纵具有重要意义。这项研究的更广泛影响包括开发新型高效电子设备的技术进步，这些设备也可以利用自旋自由度，这反过来又对量子处理很重要。 该项目为培训研究生和本科生提供了一种工具，并为亚利桑那大学科学和工程学位课程的退伍军人提供了指导和研究机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

As electronics technology is driven to produce greater memory and processing power in smaller devices, research increasingly focuses on molecules as the building blocks for electronics circuitry. Larger traditional circuit elements made of metal and semiconductor materials must conduct and store not only electrical charge, but also magnetic information. Electrons hold a negative charge, which allows them to conduct electricity when they move. Electrons also act like magnets because they possess a property called “spin”. If revolutionary molecule-based electronics are to become a reality, we must be able to understand and control how charge and spin flow not only through individual molecules, but between molecules and other materials (other parts of the circuit). In this project, funded by the Chemical Structure, Dynamics, and Mechanism-A (CSDM-A) program of the Chemistry Division, Professor Oliver Monti and his students at the University of Arizona are investigating how charge and spin flow at contact points with other materials. They are studying molecules on metal surfaces, as well as molecules on metal surfaces that have been modified with other molecules, to modify the contact condition. The Monti research group uses a combination of laser-based techniques and scanning tunneling microscopy (STM) which can image individual atoms and molecules. The research seeks to discover the important molecular structural factors that determine charge- and spin-flow in molecule based electronic elements. The graduate students receive training and experience in advanced chemistry, optical physics and atomic microscopy. This training is expected to prepare them well for the quantum information science revolution. In addition to the formal training of doctoral students, Professor Monti is developing a program for undergraduate student veterans at Arizona to gain research experience and personalized mentoring toward a successful career in science and engineering.The project focuses on tailoring the interfacial electronic structure and charge-transfer dynamics at organic semiconductor / metal interfaces. The research entails tailoring the surface electronic structure using epitaxial layers of Ag on Cu(111) to change the surface electron wavelength, the surface electron density, and the surface symmetry. The effects of these systematic changes on surface processes are examined using a combination of low-temperature scanning tunneling microscopy and steady-state and time-resolved photoemission spectroscopy. Processes such as molecular self-assembly, interfacial electronic structure and charge-transfer dynamics are thus characterized over a wide range of surface electronic properties without varying the chemical nature of the interface. Surface modifications are also being developed to facilitate Rashba splitting without the need for an external magnetic field. This study involves the adsorption of organic semiconductors that support large electric dipoles or can induce orbital mixing at the interface. If this type of Rashba splitting is achieved, it could have significant implications for the control and manipulation of spin states at organic/metal interfaces. The broader impacts of this research include the advancement of technologies to develop novel highly efficient electronic devices that may also harness the spin degrees of freedom, which in turn are important in quantum processing. This project is providing a vehicle for training both graduate and undergraduate students as well as mentoring and research opportunities for veterans enrolled in science and engineering degree programs at the University of Arizona.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.