Study of Spin-Dependent Charge Transfer through Self-Assembled Monolayers of DNA on Metal Surfaces

金属表面自组装 DNA 单层的自旋相关电荷转移研究

• 批准号: 1509794
• 负责人: Paul Weiss
• 金额: $ 42万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509794&HistoricalAwards=false
• 关键词: Study; Spin; Dependent; Charge; Transfer

Deoxyribonucleic acid (DNA) molecules, the genetic code of life, have recently been shown to possess a surprising filtering capacity for the flow of electric charge. The charge is carried by electrons that are transmitted through each molecule. Electrons also possess an intrinsic property known as spin, and can exist in one of two (usually) equally probable states: spin up or spin down. Surprisingly, DNA molecules can filter transmitted electrons based on their spin, holding exciting implications for their use in emerging technological applications that require the generation and manipulation of spin-polarized electrical currents within the nascent field of spintronics. However, the mechanism responsible for the filtering effect remains elusive and controversial. In order to assess the practicality of DNA molecules as components in next generation spintronic devices, the parameters that have been theoretically predicted to influence electron spin-filtering capacity by DNA molecules assembled on metal surfaces must be tested and determined. The proposed research will leverage two decades worth of studies on manipulating molecular assemblies and recent advances to develop and to understand spin-polarized sources of electrons. This research will combine the fields of nanoscience, nanotechnology, spintronics, bioelectronics, and biomagnetics. Specific advances in terms of experimental tests and their results will be made widely available both through UCLA, national, and global collaborations. Deeper understanding of these effects will lead to important discoveries across disciplines; findings will be broadly disseminated via presentations, publications, and strong collaborative networks. Outreach activities will target young, underrepresented scientists and the public at large by engaging local high school teachers and students, as well as the global entertainment industry based in Southern California. Recent observations of spin-selective phenomena involving chiral molecules prevalent in biological systems demonstrate the unique and exciting potential to utilize diamagnetic molecules for organic spintronics. In particular, unprecedented spin-selective electron transmission has been observed through self-assembled monolayers of deoxyribonucleic acid (DNA) adsorbed on metal surfaces. While experimental evidence has established that assembled, oriented, chiral DNA molecules have the capacity to filter electron spins at room temperature, the mechanism responsible for this phenomenon remains controversial. One community suggests that the phenomenon may be intrinsic to the molecule itself as many theoretical models attribute the observed effects to unconventional Rashba-type molecular spin-orbit coupling. In contrast, leading theory groups argue that the substrates and interfaces play major roles in spin-orbit coupling. Careful experimental tests will deconvolute the relative contributions and will establish a means to optimize spin selection and filtering. Robust figures of merit will be established to characterize spin-dependent charge transport via electrochemical methods. Molecular properties and substrate materials will be tuned systematically to test the theoretically predicted contributions to this phenomenon. Specifically, the modification of molecular chemical and electronic structures including the inclusion of heavy metal species and substrate identity will directly probe spin orbit coupling within the molecule and interface. This work will simultaneously develop a foundational understanding of spin-selective electron-molecule interactions and critically evaluate the practicability of ultimately implementing DNA and/or other chiral molecular assemblies as sources of polarized electrons in next generation organic spin electronic devices such as spin filters, spin-transfer torque magnetoresistive random access memory devices and spin-polarized organic light emitting diodes.

脱氧核糖核酸（DNA）分子，生命的遗传密码，最近被证明具有惊人的过滤能力的电荷流动。电荷由电子携带，电子通过每个分子传输。电子还具有称为自旋的固有性质，并且可以以两种（通常）同等可能的状态之一存在：自旋向上或自旋向下。令人惊讶的是，DNA分子可以根据它们的自旋过滤传输的电子，这对它们在新兴技术应用中的使用具有令人兴奋的意义，这些应用需要在自旋电子学的新生领域内产生和操纵自旋极化电流。然而，负责过滤效果的机制仍然难以捉摸和有争议。为了评估DNA分子作为下一代自旋电子器件组件的实用性，必须测试和确定理论上预测影响DNA分子组装在金属表面上的电子自旋过滤能力的参数。拟议的研究将利用20年来操纵分子组装的研究和最新进展来开发和理解电子的自旋极化源。这项研究将联合收割机结合纳米科学，纳米技术，自旋电子学，生物电子学和生物磁学领域。实验测试及其结果方面的具体进展将通过UCLA，国家和全球合作广泛提供。对这些影响的深入了解将导致跨学科的重要发现;研究结果将通过演讲，出版物和强大的合作网络广泛传播。外联活动将针对代表性不足的年轻科学家和广大公众，让当地高中教师和学生以及总部设在南加州的全球娱乐业参与。 最近的观察自旋选择性的现象，涉及手性分子在生物系统中普遍展示了独特的和令人兴奋的潜力，利用抗磁性分子的有机自旋电子学。特别是，通过吸附在金属表面的脱氧核糖核酸（DNA）的自组装单分子层，已经观察到前所未有的自旋选择性电子传输。虽然实验证据已经证实，组装的、定向的手性DNA分子具有在室温下过滤电子自旋的能力，但导致这种现象的机制仍然存在争议。一个团体认为，这种现象可能是分子本身固有的，因为许多理论模型将观察到的效应归因于非常规的Rashba型分子自旋轨道耦合。相反，领先的理论小组认为，衬底和界面在自旋轨道耦合中起主要作用。仔细的实验测试将使相对贡献去卷积，并将建立一种优化尾旋选择和过滤的方法。将建立稳健的品质因数，通过电化学方法表征自旋相关的电荷传输。分子性质和基板材料将被系统地调整，以测试理论上预测的贡献，这一现象。具体而言，分子化学和电子结构的修改，包括包括重金属物质和基板身份将直接探测分子和界面内的自旋轨道耦合。这项工作将同时发展的自旋选择性的电子分子相互作用的基础性理解和批判性地评估最终实现DNA和/或其他手性分子组件作为极化电子源在下一代有机自旋电子器件，如自旋过滤器，自旋转移矩磁阻随机存取存储器设备和自旋极化有机发光二极管的实用性。