This award supports theoretical research and education in the area of mesoscopic physics. Research focuses on the low-energy properties of mesoscopic interacting electron systems and on finding the relations between these properties and the electron transport characteristics of such systems. Electron transport in quantum wires, quantum, and mesoscopic conductors containing magnetic impurities will be studied. The project has three parts. The first part is devoted to the effect of magnetic impurities on the low-temperature conductance of mesoscopic metals. Interaction of itinerant electrons with the magnetic impurities causes relaxation of electron energy and phase, and thus affects the conductance. The rate of relaxation may be controlled by a magnetic field which polarizes impurity spins. The effect of partial spin polarization on the conductance will be studied. The second part of the project explores the properties of interacting one-dimensional electron systems beyond the Luttinger liquid model. This extension of theory is needed for the accurate description of a number of observable phenomena. This part also considers the Coulomb drag between two weakly-coupled quantum wires and electron tunneling into a quantum wire in the presence of a magnetic field. Calculation of the drag resistivity requires accounting for the dependence of electron velocity on momentum; this dependence is left out in the Luttinger liquid model. A magnetic field causes the Zeeman splitting of the electron spectrum, which results in finite-bias maxima in the differential tunneling conductance. To describe this effect, one also needs an extension of the Luttinger liquid model. The third part of the project explores the possibility of observing a violation of the Fermi-liquid behavior in a quantum dot device, a violation that is characteristic of a symmetric multi-channel Kondo problem. Here the role of inevitable deviations from the symmetry will be considered. Special emphasis will be placed also on finding ways to detect the non-Fermi-liquid behavior by studying the electron transport through such a device. This research will require a variety of condensed matter theory techniques, including diagrammatic expansions, renormalization group theory and Fermi liquid theory of the Kondo effect, the use of exactly solvable one-dimensional models, and the bosonization technique. Broader impacts of this work include education and the contribution to a base of knowledge that may form the foundation of future device technologies. This work supports the education of students and post-doctoral research associates in modern methods of condensed matter theory and nanoscale materials. The project involves the study of fundamental physics of novel systems and materials (nano-wires, quantum dots, carbon nanotubes) which are potential elements of future electronic technology. %%% This award supports theoretical research and education in mesocopic and nanoscale physics. Research focuses on the effect of electron-electron interactions on low-energy properties in low dimensional systems and on the electron transport properties of such systems. Electron transport in quantum wires (one-dimensional), quantum dots (zero-dimensional), and mesoscopic conductors containing magnetic impurities will be studied using advanced methods in theoretical condensed matter physics. The combination of low-dimensionality and electron-electron interactions in these materials and nanostructures can lead to novel electronic states that differ remarkably from those of macroscopic materials. Broader impacts of this work include education and the contribution to a base of knowledge that may form the foundation of future device technologies. This work supports the education of students and post-doctoral research associates in modern methods of condensed matter theory and in nanoscale materials. The project studies the fundamental physics of novel systems and materials (nano-wires, quantum dots, carbon nanotubes) which are potential elements of future electronic technology. ***
