794 research outputs found
Paired states of interacting electrons in a two dimensional lattice
We show that two tight binding electrons that repel may form a bounded pair
in two dimensions. The paired states form a band with energies that scale like
the strength of the interaction potential. By applying an electric field we
show that the dynamics of such states is that of a composite particle of charge
2e. The system still sustains Bloch-like states, so that if the two bands
overlap single and paired states might coexist allowing for a bosonic fluid
component that, if condensed, would decrease the resistance at low
temperatures. The presence of two bands allows for new oscillations whose
experimental detection would permit a direct measurement of the interaction
potential strength.Comment: 7 pages, 3 figure
A mesoscopic Tera-hertz pulse detector
We show that, under the passage of an electromagnetic terahertz pulse, an
asymmetric double barrier device may act as an on/off current switch, depending
on the bias. The time-dependent response of the device is discussed.Comment: 3 pages Revtex, 4 PS figures. To appear in Applied Physics Letter
Effect of Laughlin correlations on crystalline mean field solutions of the 2DEG in FQHE regime
The energy per particle of many body wavefunctions that mix Laughlin liquid
with crystalline correlations for periodic samples in the Haldane-Rezayi
configuration is numerically evaluated for periodic samples. The Monte Carlo
algorithm is employed and the wave functions are constructed in such a way that
have the same zeroes as the periodic Laughlin states. Results with up to 16
particles show that these trial wavefunctions have lower energy than the
periodic Laughlin states for finite samples even at . Preliminary
results for 36 particles suggest that this tendency could reach the
thermodynamic limit. These results get relevance in view of the very recent
experimental measures that indicate the presence of periodic structures in the
2DEG for extremely small temperatures and clean samples, inclusive at main FQHE
filling fractions .Comment: 4 pages, 1 figure, 2 table
Electron transport in interacting hybrid mesoscopic systems
A unified theory for the current through a nanoscale region of interacting
electrons connected to two leads which can be either ferromagnet or
superconductor is presented, yielding Meir-Wingreen-type formulas when applied
to specific circumstances. In such a formulation, the requirement of gauge
invariance for the current is satisfied automatically. Moreover, one can judge
unambiguously what quantities can be measured in the transport experiment
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