CAREER: Interactions and Quantum Effects in Nodal Materials

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

NONTECHNICAL SUMMARY This CAREER award supports theoretical research and education, and will explore new ways to realize new quantum mechanical phenomena in materials that emerge from the interplay of atomic structure, geometry, dimensionality, and interactions among electrons. The PI will focus on a class of materials that are related in a fundamental way to an atomically thin form of carbon known as graphene. The PI will investigate how stacking graphene layers in different ways or including other two-dimensional materials in the stack can lead to a layered material with novel electronic properties. The PI will also study whether distorting graphene can lead to superconductivity, a state of electronic matter which can transport electric current without resistance. The PI will further explore whether the superconducting state can coexist with other novel states where the motion of the electrons is strongly correlated as a consequence of their interactions. The PI will also study theoretically predicted three dimensional materials that are analogs of two dimensional graphene. These materials known as Weyl semimetals would share the property of having electronic excitations that in a fundamental sense appear to move at the speed of light. The PI will study the properties of these predicted materials which might be realized in compounds made of iridium, a rare earth, and oxygen. While of fundamental interest, the study of the properties of these new states of matter also contributes to the intellectual foundations of future electronic device technologies. The PI will seek close integration among research, experiments and education. In order to disseminate information to the general public and contribute to the general science education of society, the PI will give a series of public lectures about novel materials. The integration of teaching with research will be structured in the form of an advanced graduate course on Condensed Matter Physics, which will combine the many-body physics curriculum with current research topics. At the undergraduate level, the PI will offer a short summer course for REU students, which is designed to stimulate them to think critically about physical models and the modeling process. The PI will also seek to modernize the science curriculum of high schools through a collaboration with physics teachers. The collaboration will incorporate current research topics in the science curriculum of high schools and has the goals: to stimulate students to pursue research careers, and to increase the enrollment of high school students in physics courses. This activity is aimed to have a measurable impact in the education of high school students in the area of Oklahoma City. TECHNICAL SUMMARY This CAREER award supports theoretical research in the physics of correlated quantum systems with nodal Fermi surfaces, and aims to propose new ways to observe emergent quantum phenomena. Nodal materials are many-body Fermi systems where the Fermi surface can be continuously deformed into a set of points or lines. The structure of the bands about these nodes may have any density of states and may support a variety of different many-body states. The research will be focused on studying correlation effects, quantum phenomena and possible topological order in three classes of systems: 1. Correlated atomic multi-layer systems. Correlation effects will be investigated in twisted bilayer quasicrystals and in atomic multilayer systems, such as ABC stacked graphene trilayers. The PI will use renormalization group and non-perturbative methods to calculate physical observables in the low-energy sector and identify possible new ground states. 2. Many-body states in flat bands. The PI will study and characterize new superconducting ground states in topological flat bands and in time reversal symmetric Landau levels, which can be produced by strain in graphene and in optical lattices. 3. Quantum phenomena in Dirac and Weyl semimetals. This project will address basic questions about collective modes, transport and electronic interactions in this class of systems, whose elementary quasiparticles are Weyl fermions, which are three dimensional analogs of the chiral massless quasiparticles in graphene. The PI will seek close integration among research, experiments and education. In order to disseminate information to the general public and contribute to the general science education of society, the PI intends to give a series of public lectures about novel materials. The integration of teaching with research will be structured in the form of an advanced graduate course on Condensed Matter Physics, which will combine the many-body physics curriculum with current research topics. At the undergraduate level, the PI will offer a short summer course for REU students, which is designed to stimulate them to think critically about physical models and the modeling process. The PI will also seek to modernize the science curriculum of high schools through a collaboration with physics teachers. The collaboration will incorporate current research topics in the science curriculum of high schools and has the goals: to stimulate students to pursue research careers, and to increase the enrollment of high school students in physics courses. This activity is aimed to have a measurable impact in the education of high school students in the area of Oklahoma City.