Quantum transport in finite disordered electron systems

The thesis presents a theoretical study of electron transport in various disordered conductors. Both macroscopically homogeneous (nanoscale conductors and point contacts) and inhomogeneous (metal junctions, disordered interfaces, metallic multilayers, and granular metal films) samples have been studied using different mesoscopic as well as semiclassical (Bloch-Boltzmann and percolation in random resistor networks) transport formalisms. The main method employed is a real-space Green function technique and related Landauer-type or Kubo formula for the exact static quantum (zero temperature) conductance of a finite-size mesoscopic sample in a two-probe measuring geometry. The finite size of the sample makes is possible to treat the scattering on impurities exactly and thereby study all transport regimes. Special attention has been given to the transitional regions connecting diffusive, ballistic and localized transport regimes. Thorough analysis of the proper implementation of different formulas for the linear conductance has been provided.; The thesis has three parts. In the first Chapter of Part I the quantum transport methods have been used to extract the bulk resistivity of a three-dimensional conductor, modeled by an Anderson model on an atomic-scale lattice (composed of several thousands of atoms), from the linear scaling of disorder-averaged resistance with the length of the conductor. The second Chapter of Part I investigates transport in metal junctions, strongly disordered interfaces and metallic multilayers. Transmission properties of a single strongly disordered interface are computed.; In Part II a nanoscale quantum point contact was studied with the intention to investigate the effect of the attached leads on its conductance (i.e., the effect of "measuring apparatus" on the "result of measurement", in the sense of quantum measurement theory). The third Part is focused on transport close to the metal-insulator transition in disordered systems and effects which generate this transition in the non-interacting electron system. Special attention has been given to the so called prelocalized states which exhibit unusually high amplitudes of the wave function. The second problem of Part III is a theoretical explanation of the infrared conductivity measurement on ultrathin quench-condensed Pb films. (Abstract shortened by UMI.)...