3 research outputs found
Quantum transport through mesoscopic disordered interfaces, junctions, and multilayers
The study explores perpendicular transport through macroscopically
inhomogeneous three-dimensional disordered conductors using mesoscopic methods
(real-space Green function technique in a two-probe measuring geometry). The
nanoscale samples (containing atoms) are modeled by a tight-binding
Hamiltonian on a simple cubic lattice where disorder is introduced in the
on-site potential energy. I compute the transport properties of: disordered
metallic junctions formed by concatenating two homogenous samples with
different kinds of microscopic disorder, a single strongly disordered
interface, and multilayers composed of such interfaces and homogeneous layers
characterized by different strength of the same type of microscopic disorder.
This allows us to: contrast resistor model (semiclassical) approach with fully
quantum description of dirty mesoscopic multilayers; study the transmission
properties of dirty interfaces (where Schep-Bauer distribution of transmission
eigenvalues is confirmed for single interface, as well as for the stack of such
interfaces that is thinner than the localization length); and elucidate the
effect of coupling to ideal leads (``measuring apparatus'') on the conductance
of both bulk conductors and dirty interfaces When multilayer contains a
ballistic layer in between two interfaces, its disorder-averaged conductance
oscillates as a function of Fermi energy. I also address some fundamental
issues in quantum transport theory--the relationship between Kubo formula in
exact state representation and ``mesoscopic Kubo formula'' (which gives the
zero-temperature conductance of a finite-size sample attached to two
semi-infinite ideal leads) is thoroughly reexamined by comparing their answers
for both the junctions and homogeneous samples.Comment: 18 pages, 17 embedded EPS figure