KeywordsPhysics, Condensed Matter.
AdvisorStafford, Charles A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractIn this thesis, we have systematically investigated the stability, surface dynamics, electronic transport, and growth of metal nanowires using a semiclassical free energy functional based on the mean-field interacting electron model, which is simple and general enough. In this model, the ionic degrees of freedom of the wire are modeled as an incompressible fluid, and the conducting electrons are treated as a Fermi gas confined within the wire with Dirichlet boundary conditions. In equilibrium, we prove that the electron-electron interaction is a second-order effect to the total grand canonical free energy, while the shell-correction to the noninteracting grand canonical free energy is a first-order effect. To leading order, the electron-electron interactions just renormalize the Weyl parameters, such as the average energy density, surface tension and mean curvature energy, but not the mesoscopic shell effect. This finding for open mesoscopic systems is a generalization of the well-known Strutinsky theorem for finite-Fermion systems. It is for this reason that self-consistent jellium calculations obtain essentially identical equilibrium mesoscopic effects as calculations based on the free-electron model. However, for systems out of equilibrium, the electron-electron interaction plays important roles. First of all, the Strutinsky theorem breaks down in the non-equilibrium case. Secondly, the gauge invariance condition is violated if the electron-electron interaction is not adequately included. We first derive a thermodynamic phase diagram for jellium nanowires, which predicts that cylindrical wires with certain "magic" conductance values are stable with respect to small perturbations up to remarkably high temperatures and high applied voltage. We have shown that Jahn-Teller-distorted wires can be stable. The derived sequence of stable cylindrical and elliptical geometries explains the experimentally observed shell and supershell structures for alkali metals. Highly deformed wires can explain additional conductance peaks in low temperature experiments on alkali metals and in gold. We then study the surface dynamic properties of different phases. Both surface phonons and surface self-diffusion of atoms are included in the linearized surface dynamics. It is found that inertial dynamics (phonons) always dominate the long-wavelength behavior at small time scales, including the critical points. (Abstract shortened by UMI.)
Degree ProgramGraduate College