NSF BSF: Transport, Fluctuation, and Nonequilibrium Phase Transition in Atomically Thin Crystalline Van der Waals Superconductors

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Nontechnical Description: Superconductivity is a phenomenon where a conductor loses its resistivity entirely at low temperature, and current can flow without energy dissipation. Understanding superconductivity has been one of the most challenging physics problems for past several decades both for fundamental and applicational point of view. In this work, superconductivity in extremely thin materials will be explored by creating atomically thin superconductors with suppressed disorders. To tackle this challenging problem, scientists from Harvard University, Argonne National Laboratory, and Bar Ilan University in Israel will perform the experimental and theoretical study with complementary expertise. This research effort focuses on fundamental understanding of atomically thin crystalline superconducting materials and their structures, seeking discoveries of novel physical phenomena and exploring new quantum device concepts. Work on education and outreach projects is planned, supporting undergraduates and public school teachers. Through these research and educational projects, graduate students and undergraduates are educated in a highly interdisciplinary environment. This international team will promote interaction among the researchers by removing barriers between them through the collaboration enabled by research.Technical Description: The research focus of this project is studying fluctuation and non-equilibrium states of 2-dimensional (2D) superconductivity. Employing controlled van der Waals (vdW) heterostructure fabrication techniques developed recently, gate-tunable mesoscopic devices will be constructed, based on 2D superconducting crystals samples. The gate/temperature/magnetic field dependence of the Hall effect will be investigated to characterize emergent transport phenomena in the Bose metallic phase. Transport across the artificial magnetic pining array will be explored, realizing tunable Mott transition and vortex drag measurement to understand the superconducting anisotropy. To understand experimental results, a novel theoretical framework will be developed for understanding dynamic properties and fluctuation dynamics near non-equilibrium phase transitions. A part of this research project will also be carried out in collaboration with the expert in Israel who has complementary expertise. The novel physical phenomena emerging in the 2D vdW superconductors may enable quantum device applications. This project will also allow interdisciplinary training and education for participating postdoctoral research fellows, graduate students, undergraduate students and research interns.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.