Grainger VIP Impact Report

DANIEL RHODES Assistant Professor

Department of Materials Science and Engineering In the past year, I have continued to focus on quantum materials in the two-dimensional (2-D) limit. Two dimensional materials are atomically flat, making them easy to tune with external stimuli. Within this family of materials, I primarily focused on superconducting, topological, and magnetic behaviors. Research into these topics has resulted in two invited seminar talks, one invited conference talk (MRS fall meeting), and the funding of two proposals: a regular award from the Department of Energy and a career award from the National Science Foundation. Superconductivity is characterized by zero electrical resistance concomitant with the ability of a material to perfectly screen magnetic fields. In 2-D, it is difficult for materials to fully screen magnetic fields because of the atomically thin nature of 2-D materials. Working on 2-D superconductors, I have shown that magnetic fields can be efficiently screened, and enhanced, along directions parallel to the in-plane atoms that make up the superconductor when compared to bulk superconductors. I have illustrated that the multiple mechanisms responsible for this behavior can be discerned from one another by careful analysis of the magnetic field orientation and its impact on electrical behavior. This work has recently been submitted to Physical Review Letters. Two-dimensional quantum spin hall insulators (QSHIs) are like those that superconduct, in that conductivity exists without any electrical resistance. Different from superconductivity, this dissipationless transport of electrons only occurs along the one-dimensional edges of the 2-D QSHI material. In the past year, we have examined bulk counterparts to these materials in detail and compared their properties to few-atomic-layer devices. We have shown that strong quantum effects occur, whereas in the bulk, there were none. A manuscript on our results is currently in preparation. Funding from the Grainger Institute of Engineering was crucial for realizing these goals and receiving funding from external agencies.

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