Electron Transport in Mesoscopic Conductors
Abstract
This dissertation, divided into four main sections, presents contributions to the understanding of electron transport in mesoscopic conductors. The first section presents a simple linear response derivation of the generalized multichannel, multiprobe LandauerButtiker formula, which relates conductance to the scattering properties of the conductor. It is the first such calculation to make use of the analytic properties of the Smatrix elements. The second section develops an extension of the recursive Green's function technique to high fields, which allows numerical calculation of the transmission coefficients for an arbitrary tworeservoir phasecoherent conductor. This technique is used to study the suppression of backscatter as the mechanism for the transition from diffusive to high field transport in quantum wires. The third section considers exchangeenhanced spin splitting of Landau levels within quantum wires. This spinsplitting, as evidenced in twoterminal conductance measurements, is increased by the confinement. This is due to an effect dubbed "antiscreening", since electron electron interactions are strengthened by interaction with polarizable edgestate charge. The last section develops a general experimental approach yielding the entire transmission matrix of a multiprobe mesoscopic conductor. Using a sample design which is an almost literal realization of the LandauerButtiker model, results are presented for several new investigations enabled by this technique. Most of these investigations center on a junction in which two of the probes are separated from the main channel by quantum point contacts. This series arrangement of point contacts allows a sensitive momentum spectroscopy of the emitted distribution. Even in the case of a single propagating mode, surprising modal features in the outgoing distribution are observed. This indicates new details about the potentials within quantum point contacts. In particular, it indicates that conductance quantization can be present even in the presence of non adiabatic potentials and significant mode conversion. This pinch geometry also allows the first fullycharacterized realization of weaklycoupled probes.
 Publication:

Ph.D. Thesis
 Pub Date:
 1992
 Bibcode:
 1992PhDT.......229S
 Keywords:

 GALLIUM ARSENIDE;
 Physics: Condensed Matter; Engineering: Electronics and Electrical