Arisato Kawabata

Electron conduction in one-dimensional system is investigated explicitly taking into account the reservoirs to which 1D channel is connected at its ends. We calculate the current driven by the chemical potential difference of two reservoirs, using the linear response theory by Kubo. At 0K, the conductance of 1D channel is expressed in terms of one-electron Green's functions even in the presence of the interaction, in contrast to the theory based on Kubo formula, in which two-electron Green's functions are essentially involved. The formalism in this paper provides a new interpretation of Landauer formula. As regards the interaction effects, the conductance of Fermi liquid without potential scattering is 2e(2)/h, while that of Tomonaga-Luttinger liquid deceases with power low as the length of LD channel increases.

Electron transport of interacting electrons in a quantum wire is investigated. The resistance is calculated in the lowest order in the impurity potential taking account of the electron-electron interaction in the form of the vertex correction to the interaction with the impurities. To calculate the vertices we use the parquet diagram method, and the results by the renormalization group method on the transmission of single barrier are reproduced in the lowest order in the impurity potential. The case of coulomb interaction is investigated also and it is pointed out that the temperature dependence of the resistance is qualitatively equal to that for short-range interaction.

Boundary roughness scattering in quantum wires is investigated. A new formulation to construct an effective potential beyond the perturbation theory and the adiabatic approximation is proposed. The theory of scattering in quasi-one dimensional systems which was proposed by the author to account for the higher order perturbation is re-investigated and is applied to a single-subband wire in the presence of screening by conduction electrons. Effects of screening in a multi-subband wire is also investigated and it is shown, at least for two-subband wires, that at low temperatures the currents carried by each subband become equal because of the peculiarity of the screening in quasi one-dimensional systems.

Electron transport through a quantum dot is discussed from the point of view of the Friedel sum rule. When an odd number of electrons are in the dot, the localized moment may be formed because of the Coulomb repulsion between the electrons. In this situation, it is predicted that the transmission probability of an electron through the dot is almost unity if the temperature is lower than the Kondo temperature, i.e., the characteristic energy of the spin fluctuations divided by Boltzmann constant.

Weak localization theory of magnetoresistance in two-dimensional systems is re-investigated.A formulation is developed which is applicable up to magnetic field much larger than the exsisting theory.The result of the calculation is compared with the experiment on GaAs/AlGaAs heterojunction andthe agreement between them is satisfactory. © 1984, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.