2,436 research outputs found
Coherent transport in disordered metals out of equilibrium
We derive a formula for the quantum corrections to the electrical current for
a metal out of equilibrium. In the limit of linear current-voltage
characteristics our formula reproduces the well known Altshuler-Aronov
correction to the conductivity of a disordered metal. The current formula is
obtained by a direct diagrammatic approach, and is shown to agree with what is
obtained within the Keldysh formulation of the non-linear sigma model. As an
application we calculate the current of a mesoscopic wire. We find a
current-voltage characteristics that scales with , and calculate the
different scaling curves for a wire in the hot-electron regime and in the
regime of full non-equilibrium.Comment: 16 pages, 13 figure
Coherent transport in disordered metals: zero dimensional limit
We consider non-equilibrium transport in disordered conductors. We calculate
the interaction correction to the current for a short wire connected to
electron reservoirs by resistive interfaces. In the absence of charging effects
we find a universal current-voltage-characteristics. The relevance of our
calculation for existing experiments is discussed as well as the connection
with alternative theoretical approaches
Quasiclassical theory of charge transport in disordered interacting electron systems
We consider the corrections to the Boltzmann theory of electrical transport
arising from the Coulomb interaction in disordered conductors. In this article
the theory is formulated in terms of quasiclassical Green's functions. We
demonstrate that the formalism is equivalent to the conventional diagrammatic
technique by deriving the well-known Altshuler-Aronov corrections to the
conductivity. Compared to the conventional approach, the quasiclassical theory
has the advantage of being closer to the Boltzmann theory, and also allows
description of interaction effects in the transport across interfaces, as well
as non-equilibrium phenomena in the same theoretical framework. As an example,
by applying the Zaitsev boundary conditions which were originally developed for
superconductors, we obtain the -theory of the Coulomb blockade in tunnel
junctions. Furthermore we summarize recent results obtained for the
non-equilibrium transport in thin films, wires and fully coherent conductors.Comment: 46 pages; review articl
Onsager relations in a two-dimensional electron gas with spin-orbit coupling
Theory predicts for the two-dimensional electrons gas with only Rashba
spin-orbit interaction a vanishing spin Hall conductivity and at the same time
a finite inverse spin Hall effect. We show how these seemingly contradictory
results are compatible with the Onsager relations: the latter do hold for spin
and particle (charge) currents in the two-dimensional electron gas, although
(i) their form depends on the experimental setup and (ii) a vanishing bulk spin
Hall conductivity does not necessarily imply a vanishing spin Hall effect. We
also discuss the situation in which extrinsic spin orbit from impurities is
present and the bulk spin Hall conductivity can be different from zero.Comment: Accepted versio
Non-linear conductivity and quantum interference in disordered metals
We report on a novel non-linear electric field effect in the conductivity of
disordered conductors. We find that an electric field gives rise to dephasing
in the particle-hole channel, which depresses the interference effects due to
disorder and interaction and leads to a non-linear conductivity. This
non-linear effect introduces a field dependent temperature scale and
provides a microscopic mechanism for electric field scaling at the
metal-insulator transition. We also study the magnetic field dependence of the
non-linear conductivity and suggest possible ways to experimentally verify our
predictions. These effects offer a new probe to test the role of quantum
interference at the metal-insulator transition in disordered conductors.Comment: 5 pages, 3 figure
Simulation Studies of the NLC with Improved Ground Motion Models
The performance of various systems of the Next Linear Collider (NLC) have
been studied in terms of ground motion using recently developed models. In
particular, the performance of the beam delivery system is discussed. Plans to
evaluate the operation of the main linac beam-based alignment and feedback
systems are also outlined.Comment: Submitted to XX International Linac Conferenc
Current-induced spin polarization and the spin Hall effect: a quasiclassical approach
The quasiclassical Green function formalism is used to describe charge and
spin dynamics in the presence of spin-orbit coupling. We review the results
obtained for the spin Hall effect on restricted geometries. The role of
boundaries is discussed in the framework of spin diffusion equations.Comment: 10 pages, 5 figures, Submitted to Solid State Communications Special
Issue on "Fundamental Phenomena in Low Dimensional Electron Systems". Special
Issue Editors: Marco Polini, Michele Governale, Hermann Grabert, Vittorio
Pellegrini, and Mario Tos
NLC Luminosity as a Function of Beam Parameters
Realistic calculation of NLC luminosity has been performed using particle
tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various
values of beam emittance, energy and beta functions at the Interaction Point
(IP). Results of the simulations are compared with analytic luminosity
calculations. The optimum range of IP beta functions for high luminosity was
identified.Comment: 4 pages, 7 figure
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