1,303 research outputs found
Harper-Hofstadter problem for 2D electron gas with -linear Rashba spin-orbit coupling
The Harper-Hofstadter problem for two-dimensional electron gas with Rashba
spin-orbit coupling subject to periodic potential and perpendicular magnetic
field is studied analytically and numerically. The butterfly-like energy
spectrum, spinor wave functions as well as the spin density and average spin
polarization are calculated for actual parameters of semiconductor structure.
Our calculations show that in two-dimensional electron gas subject to periodic
potential and uniform magnetic field the effects of energy spectrum splitting
caused by large spin-orbit Rashba coupling can be observed experimentally.Comment: 8 pages, 6 figures. submitted to Europhys. Letter
Evidence for magnetoplasmon character of the cyclotron resonance response of a two-dimensional electron gas
Experimental results on the absolute magneto-transmission of a series of high
density, high mobility GaAs quantum wells are compared with the predictions of
a recent magnetoplasmon theory for values of the filling factor above 2. We
show that the magnetoplasmon picture can explain the non-linear features
observed in the magnetic field evolution of the cyclotron resonance energies
and of the absorption oscillator strength. This provides experimental evidence
that inter Landau level excitations probed by infrared spectroscopy need to be
considered as many body excitations in terms of magnetoplasmons: this is
especially true when interpreting the oscillator strengths of the cyclotron
transitions
Double-exciton component of the cyclotron spin-flip mode in a quantum Hall ferromagnet
We report on the calculation of the cyclotron spin-flip excitation (CSFE) in
a spin-polarized quantum Hall system at unit filling. This mode has a
double-exciton component which contributes to the CSFE correlation energy but
can not be found by means of a mean field approach. The result is compared with
available experimental data.Comment: 9 pages, 2 figure
Interacting fermions in two dimensions: beyond the perturbation theory
We consider a system of 2D fermions with short-range interaction. A
straightforward perturbation theory is shown to be ill-defined even for an
infinitesimally weak interaction, as the perturbative series for the
self-energy diverges near the mass shell. We show that the divergences result
from the interaction of fermions with the zero-sound collective mode. By
re-summing the most divergent diagrams, we obtain a closed form of the
self-energy near the mass shell. The spectral function exhibits a threshold
feature at the onset of the emission of the zero-sound waves. We also show that
the interaction with the zero sound does not affect a non-analytic,
-part of the specific heat.Comment: 5 pages, 4 figure
Observation of exchange Coulomb interactions in the quantum Hall state at nu=3
Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are
determined from two inter-Landau level spin-flip excitations measured by
resonant inelastic light scattering. The two coupled collective excitations are
linked to inter-Landau level spin-flip transitions arising from the N=0 and N=1
Landau levels. The strong repulsion between the two spin-flip modes in the
long-wave limit is clearly manifested in spectra displaying Coulomb exchange
contributions that are comparable to the exchange energy for the quantum Hall
state at nu=1. Theoretical calculations within the Hartree-Fock approximation
are in a good agreement with measured energies of spin-flip collective
excitations.Comment: 5 pages, 3 figures, to appear in PRB Rapid Communication
Topologically Induced Optical Activity in Graphene-Based Meta-Structures
Non-reciprocity and asymmetric transmission in optical and plasmonic systems
is a key element for engineering the one-way propagation structures for light
manipulation. Here we investigate topological nanostructures covered with
graphene-based meta-surfaces, which consist of a periodic pattern of
sub-wavelength stripes of graphene winding around the (meta-) tube or
(meta-)torus. We establish the relation between the topological and plasmonic
properties in these structures, as justified by simple theoretical expressions.
Our results demonstrate how to use strong asymmetric and chiral plasmonic
responses to tailor the electrodynamic properties in topological
meta-structures. Cavity resonances formed by elliptical and hyperbolic plasmons
in meta-structures are sensitive to the one-way propagation regime in a finite
length (Fabry-Perot-like) meta-tube and display the giant mode splitting in a
(Mach-Zehnder-like) meta-torus.Comment: 20 pages, 5 figures + TOC figure, accepted by ACS Photonic
Turbulence in Binary Bose-Einstein Condensates Generated by Highly Non-Linear Rayleigh-Taylor and Kelvin-Helmholtz Instabilities
Quantum turbulence (QT) generated by the Rayleigh-Taylor instability in
binary immiscible ultracold 87Rb atoms at zero temperature is studied
theoretically. We show that the quantum vortex tangle is qualitatively
different from previously considered superfluids, which reveals deep relations
between QT and classical turbulence. The present QT may be generated at
arbitrarily small Mach numbers, which is a unique property not found in
previously studied superfluids. By numerical solution of the coupled
Gross-Pitaevskii equations we find that the Kolmogorov scaling law holds for
the incompressible kinetic energy. We demonstrate that the phenomenon may be
observed in the laboratory.Comment: Revised version. 7 pages, 8 figure
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