Spectroscopic Properties of Two-Dimensional Superconductors

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Non-technical Abstract: Superconductors are special states of solid matter. Understanding what makes solids superconducting is a grand goal of physics research, useful in the emerging fields of quantum communication and computation. Recently, a number of new superconductors have been discovered in layered van der Waals materials that are crystalline in nature. But the mechanisms of superconductivity and the consequences of the superconducting state to the observed properties are still unknown. In this project, scanning tunneling microscopy will be used to understand the quantum mechanical properties of these new classes of materials at the atomic scale. Research performed in this project will be used to develop new modules for high school and undergraduate education. The project will also provide science and technical education opportunities for students at levels from high school upwards.Technical Abstract: Superconductivity in two dimensions remains an intellectual frontier in condensed matter physics with fundamental open problems in understanding pairing mechanisms and fluctuations and their consequences for the observed spectroscopic and transport properties. Recently, it has become possible to create crystalline two-dimensional superconductors that are only a few unit cells thick. These include mechanically exfoliated bulk superconductors such as niobium diselenide as well as new emergent superconductors such as twisted bilayer graphene. This project will use scanning tunneling microscopy and spectroscopy to gain insight into the local density of states in these new classes of superconductors. Interference experiments will be used to gain insight into the symmetry and structure of superconducting gaps. Measurements in applied magnetic fields will also be used to gain insight into vortex motion and fluctuations in these materials which can often be in the clean limit where the mean free path is much larger than the size of vortices.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.