Tunable topological hybrid materials via interface- and topology-engineered heterostructures

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Nontechnical Description:A new class of materials called topological materials has emerged with attractive properties for making exotic electronic and quantum devices. However, these properties are affected by defects which hamper their potential applications. This project provides a novel way of controlling these defects as well as developing tunable hybrid materials by combining a variety of topological and non-topological materials. Availability of more topological materials with superior or new properties enables development of technology for quantum computing and quantum information. The project includes close collaboration with many other researchers. Postdocs, graduate and undergraduate students recruited from underrepresented groups receive training and mentoring to become next generation leaders in thin film quantum materials. Planned outreach activities to local elementary schools foster positive images of science and scientists to the broad community.Technical Description:Topology has emerged as a new paradigm of classifying electronic materials over the past decade, and a series of topological materials including topological insulators and topological semimetals have been discovered. However, native defects, working as self-dopants, have long been a major hurdle in the way to reaching the quantum regime of the topological states. In recent years, the principle investigator has demonstrated that majority of these defects originate from interfaces and with proper interface-engineering schemes, most of these defects can be eliminated. Furthermore, it was shown that topology and other critical properties of certain topological materials can be continuously tuned through thin film engineering schemes such as solid mixing and digital layering. However, most of the topological materials investigated so far have been thermodynamically-defined compounds. This project seeks to extend the boundary of topological materials beyond the thermodynamic limit and search for new topological phenomena by developing a series of tunable artificial topological materials with various thin film engineering schemes such as solid-mixing, digital-layering, dimensional confinement, and interfacial defect engineering. By combining a variety of interface and topology-engineering schemes, this project develops tunable topological hybrid materials and explore yet-to-be-discovered topological quantum effects, along two Thrusts: 1. Tunable artificial topological materials and 2. Tunable interfacial topological superconductors. These materials allow exploring the boundaries between kinetically vs thermodynamically-driven growth landscapes and uncovering new physics where topology, magnetism and superconductivity meet, including and beyond minimal magnetic Weyl semimetals, high temperature quantum anomalous Hall phase, axion insulators, and interfacial superconductivity.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.