773 research outputs found
Specific Plateaus of the Quantum Hall Effect Induced by an Applied Bias
The spectrum and the eigenstates of a finite 2D tight-binding electronic
system, with Dirichlet boundary conditions, in magnetic field and external
linear potential are studied. The eigenstates show an equipotential character
and may cross the plaquette in the direction perpendicular to the electric
field. When leads are added to the plaquette, the channels carrying the current
may be shortcut by equipotentials, resulting in additional plateaus situated
inbetween the usual IQHE plateaus. This idea is confirmed by a numerical
calculation within the four-terminal Landauer-B\"{u}ttiker approach.Comment: 9 pages, revtex, 2 gif figures and 5 postscript figure
Coulomb effects on the transport properties of quantum dots in strong magnetic field
We investigate the transport properties of quantum dots placed in strong
magnetic field using a quantum-mechanical ' approach based on the 2D
tight-binding Hamiltonian with direct Coulomb interaction and the
Landauer-B\"{u}ttiker (LB) formalism. The electronic transmittance and the Hall
resistance show Coulomb oscillations and also prove multiple addition
processes. We identify this feature as the 'bunching' of electrons observed in
recent experiments and give an elementary explanation in terms of spectral
characteristics of the dot. The spatial distribution of the added electrons may
distinguish between edge and bulk states and it has specific features for
bunched electrons. The dependence of the charging energy on the number of
electrons is discussed for strong and vanishing magnetic field. The crossover
from the tunneling to quantum Hall regime is analyzed in terms of dot-lead
coupling.Comment: 17 pages,8 figures,Revtex,submitted to Physical Review
Spin-flip Effects in the Mesoscopic Spin-Interferometer
We investigate the properties of the electron spin-transmission through an
Aharonov-Bohm interferometer with an embedded multilevel quantum dot containing
magnetic impurities. A suitable formalism is developed. The amplitude and the
phase of the flip- and nonflip-transmittance are calculated numerically as
function of the magnetic field and the gate potential applied on the dot. The
effects induced by the exchange interaction to spin-dependent
magnetoconductance fluctuations and transmittance phase are shown.Comment: 10 pages, 9 figure
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