Symmetry, entanglement, and far-from equilibrium perturbations in 2D materials

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

Non-technical Abstract: A crystal lattice is the geometrical arrangement of atoms inside a crystal. Theoretical approaches often rely on the assumption that materials have perfectly periodic lattices. However, in reality, disorder - in the form of defects, vacancies, or some other cooperative atomistic modulation - is quite common and relevant to the underlying interactions and can be the driver for new and interesting behaviors. The goal of this project is to advance fundamental knowledge on the role and properties of the crystal lattice across variable length and time scales, allowing for predictions of physical properties. Specifically, a family of quasi-two dimensional compounds known as transition metal dichalcogenides (TMDs) will be investigated as they offer an incredibly rich range of novel and poorly understood properties. Constructed by simple stacking principles, layers of a transition metal alternate with a chalcogen ion. TMDs are important in a broad scientific context, and can find their way to many technologies because of their tunable characteristics. This project seeks to identify universal features of TMDs and ways to control their properties. Novel pump-probe experimental techniques and neutron scattering will be used in the course of this study, providing students with training opportunities in cutting-edge experimental techniques and exposing them to novel capabilities. Technical Abstract: Theoretical approaches often rely on the assumption that materials have perfectly periodic lattices but, in reality, disorder - in the form of defects, vacancies, or some other cooperative atomistic modulation - is quite common and relevant to the underlying interactions and can be the driver for new and interesting behaviors. The primary objective of this project is to identify lattice distortions at relevant length and time scales, and their effects on how spins and electrons self-organize in real materials - new local patterns that define the characteristic charge density wave (CDW) modulations as well as new magnetic signatures that might serve as evidence of quantum spin liquids (QSLs) in 1T-MX2 (M = Ta, and X = S, Se, or Te). This project provides the opportunity to explore an exotic form of superconductivity given its close proximity to QSL and seeks to obtain a fundamental understanding of CDW-enabled transitions to superconducting and QSL states. The effects of disorder and reduced dimensionality on the static and dynamic properties, at thermal equilibrium and away from equilibrium will be studied through isovalent doping. The research combines high-resolution and high-intensity neutron and x-ray scattering techniques, as well as real-space analysis probes, using single crystals and powders, supplemented by thermodynamic measurements. 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.