Quantum Transport in Strongly Correlated Metals and Superconductors

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

This grant supports research to develop and advance theoretical and computational tools for analyzing the behavior of electrons governed by long-range and/or retarded (singular) interactions in the presence of quenched disorder. In recent years it has become increasingly clear that the traditional methods of Fermi liquid theory fail to provide a proper description of systems of electrons with singular interactions. Such interactions can be either of Coulomb origin or they can result from effective description of some short-range (e.g., screened), yet sufficiently strong, forces acting between electrons. The effects of singular interactions become even more pronounced in the presence of disorder as well as in low dimensions and/or restricted geometries, the situation often encountered in nanostructures. Due to the complexity of the problem, powerful analytical and numerical methods are required including Keldysh functional integral and quantum kinetic equation, diagrammatic techniques and renormalization group, non-perturbative eikonal method and bosonization. These common theoretical tools provide a unifying framework, within which the following topics will be considered: interference between disorder and inelastic electron scattering near quantum critical transitions in itinerant magnets; quasiparticles in normal and superconducting states of dirty d-wave superconductors; transport properties of compressible states of electrons in strong magnetic fields. This research aims at developing an adequate description of, and gaining new insight into, the nature and classification of the observed anomalous (apparently non-Fermi liquid) behaviors in a variety of strongly correlated electron systems; interpreting experimental data and proposing new experiments on transport properties and spectroscopy of heavy fermion compounds, high-Tc cuprates, and the single- and double-layer two-dimensional electron gas in strong magnetic fields; linking the properties of the novel magnetic and superconducting materials to their structure and assessing feasibility of their practical applications. %%% This grant supports research to develop and advance theoretical and computational tools for analyzing the behavior of electrons governed by long-range and/or retarded (singular) interactions in the presence of quenched disorder. In recent years it has become increasingly clear that the traditional methods of Fermi liquid theory fail to provide a proper description of systems of electrons with singular interactions. Such interactions can be either of Coulomb origin or they can result from an effective description of some short-range (e.g., screened), yet sufficiently strong, forces acting between electrons. The effects of singular interactions become even more pronounced in the presence of disorder as well as in low dimensions and/or restricted geometries, the situation often encountered in nanostructures. The research will apply a number of powerful analytical and numerical methods to deal with this general class of problems and its manisfestations in the cuprate superconductors, quantum Hall and heavy fermion systems. While much of this work is of a fundamental nature, the results may well have long-range impacts on future technologies. ***