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

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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.