Collaborative Research: Spin Correlations and Spin-Orbit Effects in New Quantum Materials

University Of Florida, Gainesville FL

Investigators

Abstract

NON-TECHNICAL SUMMARY This award supports collaborative research and educational activities carried out among theory groups at Ohio University and the University of Florida, working in close connection with scientists in Argentina and Brazil, to combine techniques and expertise and tackle important and topical problems in materials research. The project will focus on exploring electronic properties of materials where the electron's spin degree of freedom is strongly affected by their spatial (orbital) motion. The coupling of spin and orbital degrees of freedom is a recently rediscovered phenomenon that has been observed to impact a number of properties in metals, semiconductors, and insulators, and can be enhanced by applied electric fields. The research to be carried out is designed to provide a widely applicable description of how spin-orbit interactions compete with repulsive electron-electron interactions under different external fields and microscopic environments. This description will be applied to decorated or intercalated graphene (a two-dimensional material made of carbon atoms that is one atom thick), other two-dimensional single crystals, and three-dimensional materials in which the energy of the electronic excitations is linearly proportional to their momentum. The project is expected to provide fundamental insights into the consequences of spin-orbit interactions as well as to advance the understanding of materials for better experimental characterization and eventual device applications in magnetism, spin-sensitive electronics, and quantum information processing. The project team also plans a number of educational activities across its different sites, including the training of junior researchers in the US and Latin America, as well as outreach efforts that bring in writers to produce engaging books for a general K-12 audience on topics related to the research. TECHNICAL SUMMARY This award will support theoretical research and educational activities aimed at achieving a fundamental understanding of spin-orbit interactions and their competition with Coulomb repulsion in recently discovered materials that include graphene and its derivatives, two-dimensional dichalcogenides and Kagome crystals, three-dimensional Dirac semimetals, and their heterostructures. In addition to their fascinating and somewhat exotic physical properties, these materials promise a variety of exciting technological applications, from magnetics and spintronics to new carbon-based devices, and even quantum information processing. The project team plans to employ and further develop appropriate theoretical techniques, including the numerical renormalization group, the density-matrix renormalization group, and continuous and tight-binding scattering-matrix approaches, as well as field-theoretical representations of low-energy effective Hamiltonians for the systems of interest. These approaches are proven and reliable in treating strongly correlated problems, and their complementarity gives the collaboration a unique advantage. The research team consisting of theory groups at Ohio University and the University of Florida, working in close collaboration with scientists in Argentina and Brazil, will seek to advance the techniques to enhance their range of applicability, especially in connection with time-dependent and non-equilibrium phenomena. Competition between phases of matter, and their control and modification through external probes, are the two main issues to be investigated. A particular focus will be on understanding and guiding experimental developments, with the goal of elucidating the role that intrinsic quantum symmetries play in the presence of external electromagnetic and strain fields. The project team also plans a number of educational activities across its different sites, including the training of junior researchers in the US and Latin America, as well as outreach efforts that bring in writers to produce engaging books for a general K-12 audience on topics related to the research.