CAREER: Probing and Manipulating Electronic and Spin Degrees of Freedom in Paramagnetic Single Molecule Circuits

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。在化学系化学结构、动力学和机理A项目的支持下，波士顿大学的Maria Kamenetska博士正在研究连接到电路中的单个顺磁分子的电子和磁性。将分子用作开关、晶体管或量子比特，可以开发出比现有电子设备更小、更强大的电子设备。对这种应用特别感兴趣的是顺磁分子，它具有固有的磁性，使其成为非易失性存储器和量子信息科学应用的候选者。Maria Kamenetska和她的团队使用一种基于扫描隧道显微镜的方法来测量通过与金属电极结合的单个分子的电流。这些实验测量与计算研究相辅相成，以阐明化学环境如何影响所得分子电路的电子和磁性能。了解电极和顺磁分子之间的化学相互作用可以提高电路的可靠性、控制和功能，在单分子电路中具有磁传感和门控的潜力。更广泛的影响集中在培养分子科学，电子和量子技术界面的多样化和量子素养的劳动力，以及建立和改进课程，并指导波士顿大学新实施的化学和物理本科专业的学生。本研究旨在确定化学设计原则和纳米操作技术，以形成稳健的单顺磁分子电路，并研究它们的新兴电子和自旋自由度。实验方法，如无机合成和扫描隧道显微镜断结（STMBJ）单分子电导测量与密度泛函理论（DFT）和非平衡格林函数（NEGF）计算技术相结合，实现了磁功能单分子电路的全面和迭代研究。使用电化学STM配置进行了三个终端电测量，以揭示金属分子化学对结电子自由度的影响，而铁磁电极上的STMBJ测量允许自旋分辨电子输运测量。DFT计算支持实验工作，并进一步深入了解金属分子结的结构-性质关系。更广泛的影响集中在分子科学，电子和量子技术界面的学生培训上。新开设的化学与物理本科专业，旨在促进多样性和包容性，为鼓励早期职业阶段的跨学科科学创造一个环境。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).With the support of the Chemical Structure, Dynamics, and Mechanisms A Program in the Division of Chemistry, Dr. Maria Kamenetska of Boston University is investigating the electronic and magnetic properties of single paramagnetic molecules wired into an electric circuit. The use of molecules as switches, transistors, or qubits could enable the development of smaller and more powerful electronic devices than what is currently available. Of particular interest for this application are paramagnetic molecules, which have intrinsic magnetic properties, making them candidates for applications in non-volatile memory and in quantum information science. Maria Kamenetska and her group use an approach based on scanning tunneling microscopy to measure current through a single molecule bound to metal electrodes. These experimental measurements are complemented with computational investigations to elucidate how the chemical environment influences the electronic and magnetic properties of the resulting molecular circuits. Understanding chemical interactions between the electrodes and paramagnetic molecule can improve circuit reliability, control, and functionality, with potential for magnetic sensing and gating in single molecule circuits. Broader impacts focus on training a diverse and quantum-literate workforce at the interface of molecular science, electronics and quantum technology as well as building and improving the curriculum of and mentoring students in the newly-implemented Chemistry and Physics undergraduate major at Boston University.This research aims to identify chemical design principles and nano-manipulation techniques for forming robust single paramagnetic molecule circuits and to investigate their emergent electronic and spin degrees of freedom. Experimental approaches, such as inorganic synthesis and scanning tunneling microscope break junction (STMBJ) single molecule conductance measurements are coupled with density functional theory (DFT) and non-equilibrium green function (NEGF) computational techniques to achieve a comprehensive and iterative study of magnetically-functional single molecule circuits. Three terminal electrical measurements are performed using an electrochemical STM configuration to reveal the effect of metal-molecule chemistry on electronic degrees of freedom of the junction, while STMBJ measurements on ferromagnetic electrodes allow spin-resolved electron transport measurements. DFT calculations support the experimental work and provide further insight into structure-property relationships in metal-molecule junctions. The broader impacts focus on student training at the interface of molecular science, electronics and quantum technology. A newly developed Chemistry and Physics undergraduate major, that aims to promote diversity and inclusion, serves to create of an environment that encourages interdisciplinary science at an early career stage.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.