3,700 research outputs found
Coulomb drag between one-dimensional conductors
We have analyzed Coulomb drag between currents of interacting electrons in
two parallel one-dimensional conductors of finite length attached to
external reservoirs. For strong coupling, the relative fluctuations of electron
density in the conductors acquire energy gap . At energies larger than
, where
is the impurity scattering rate, and for , where is the
fluctuation velocity, the gap leads to an ``ideal'' drag with almost equal
currents in the conductors. At low energies the drag is suppressed by coherent
instanton tunneling, and the zero-temperature transconductance vanishes,
indicating the Fermi liquid behavior.Comment: 5 twocolumn pages in RevTex, added 1 eps-Figure and calculation of
trans-resistanc
Theoretical Prerequisites for the Creation of a Dynamic Model of the Process of Displacement of the Earth's Surface
Quantum critical behaviour of the plateau-insulator transition in the quantum Hall regime
High-field magnetotransport experiments provide an excellent tool to
investigate the plateau-insulator phase transition in the integral quantum Hall
effect. Here we review recent low-temperature high-field magnetotransport
studies carried out on several InGaAs/InP heterostructures and an InGaAs/GaAs
quantum well. We find that the longitudinal resistivity near the
critical filling factor ~ 0.5 follows the universal scaling law
, where . The critical exponent equals ,
which indicates that the plateau-insulator transition falls in a non-Fermi
liquid universality class.Comment: 8 pages, accepted for publication in Proceedings of the Yamada
Conference LX on Research in High Magnetic Fields (August 16-19, 2006,
Sendai
Fractional charge in transport through a 1D correlated insulator of finite length
Transport through a one channel wire of length confined between two leads
is examined when the 1D electron system has an energy gap : induced by the interaction in charge mode (: charge velocity in the
wire). In spinless case the transformation of the leads electrons into the
charge density wave solitons of fractional charge entails a non-trivial low
energy crossover from the Fermi liquid behavior below the crossover energy to the insulator one with the
fractional charge in current vs. voltage, conductance vs. temperature, and in
shot noise. Similar behavior is predicted for the Mott insulator of filling
factor .Comment: 5 twocolumn pages in RevTex, no figure
Threshold features in transport through a 1D constriction
Suppression of electron current through a 1D channel of length
connecting two Fermi liquid reservoirs is studied taking into account the
Umklapp electron-electron interaction induced by a periodic potential. This
interaction causes Hubbard gaps for . In the perturbative
regime where ( charge velocity), and for small deviations
of the electron density from its commensurate values
can diverge with some exponent as voltage or temperature decreases above
, while it goes to zero below . This results
in a nonmonotonous behavior of the conductance.Comment: Final variant published in PRL, 79, 1714; minor correction
Transport properties of single channel quantum wires with an impurity: Influence of finite length and temperature on average current and noise
The inhomogeneous Tomonaga Luttinger liquid model describing an interacting
quantum wire adiabatically coupled to non-interacting leads is analyzed in the
presence of a weak impurity within the wire. Due to strong electronic
correlations in the wire, the effects of impurity backscattering, finite bias,
finite temperature, and finite length lead to characteristic non-monotonic
parameter dependencies of the average current. We discuss oscillations of the
non-linear current voltage characteristics that arise due to reflections of
plasmon modes at the impurity and quasi Andreev reflections at the contacts,
and show how these oscillations are washed out by decoherence at finite
temperature. Furthermore, the finite frequency current noise is investigated in
detail. We find that the effective charge extracted in the shot noise regime in
the weak backscattering limit decisively depends on the noise frequency
relative to , where is the Fermi velocity, the
Tomonaga Luttinger interaction parameter, and the length of the wire. The
interplay of finite bias, finite temperature, and finite length yields rich
structure in the noise spectrum which crucially depends on the
electron-electron interaction. In particular, the excess noise, defined as the
change of the noise due to the applied voltage, can become negative and is
non-vanishing even for noise frequencies larger than the applied voltage, which
are signatures of correlation effects.Comment: 28 pages, 19 figures, published version with minor change
Quantum-Hall activation gaps in graphene
We have measured the quantum-Hall activation gaps in graphene at filling
factors and for magnetic fields up to 32 T and temperatures
from 4 K to 300 K. The gap can be described by thermal excitation to
broadened Landau levels with a width of 400 K. In contrast, the gap measured at
is strongly temperature and field dependent and approaches the expected
value for sharp Landau levels for fields T and temperatures
K. We explain this surprising behavior by a narrowing of the lowest Landau
level.Comment: 4 pages, 4 figures, updated version after review, accepted for PR
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