CAREER: Tunable Connate Topological Superconductivity in 2D Transition Metal Dichalcogenides

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Non-Technical Abstract: Superconducting and quantum-based technologies are promising avenues for realizing faster and more efficient computation, energy-efficient transport of electricity, and novel methods that enhance the capabilities of materials metrology. One scheme for realizing robust reading of quantum states for such technologies is to combine superconductivity with electronic states that only exist at the edges of materials, resulting in a special state that merges these two properties: connate topological superconductivity. Few-layer transition metal dichalcogenides are a promising subclass of materials that have been predicted to exhibit connate topological superconductivity and are highly tunable with moderate changes to the electrostatic environment. In this project, the research team aims to discover, develop, and electrostatically control connate topological superconducting behavior in semimetallic and superconducting transition metal dichalcogenides. The success of this project will introduce new methods with which to probe novel forms of superconductivity and lead to greater insight into the general mechanisms that govern superconductivity. In addition, this project integrates graduate and undergraduate students into the research effort and develops and runs outreach activities for K-12 students in collaboration with teachers from local school districts. Technical Abstract: A two-dimensional connate topological superconductor is a unique system where the bulk interior of a two-dimensional material exhibits superconductivity while the edge simultaneously hosts a topologically nontrivial state. As a result, the bulk superconductivity induces superconductivity in the nontrivial edge states, giving rise to superconducting edge states. The goal of this project is to discover, develop, and electrostatically control connate topological superconductivity and the concomitant superconducting edge states in noncentrosymmetric, T’ and Td, two-dimensional superconductors. Connate topological superconductivity has been proposed for a number of bulk materials, but the experimental evidence for and manipulation of connate topological superconductivity has remained limited due to strong electronic screening caused by a large concentration of charge carriers across many atomic layers. Atomically thin T’ and Td superconductors with moderate charge carrier concentrations offer an opportunity to better understand and control connate topological superconductivity phenomena. Because of the low electronic screening, the behavior of two-dimensional connate topological superconductors may be tuned without introducing disorder via electrostatic gating. Realizing a connate topological superconductor and the associated superconducting edge states, which are beyond the scope of standard Bardeen-Cooper-Schrieffer theory, would give crucial insight into how superconductivity can emerge without strictly being facilitated by phonons and could be useful for engineering qubits with long coherence times. 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.