401 research outputs found
Second harmonic generation at the edge of a two-dimensional electron gas
We show that driving a two-dimensional electron gas by an in-plane electric
field oscillating at the frequency gives rise to an electric current
at flowing near the edge of the system. This current has both
parallel and perpendicular to the edge components, which emit electromagnetic
waves at with different polarizations. We develop a microscopic
theory of such an edge second harmonic generation and calculate the edge
current at in different regimes of electron transport and electric
field screening. We also show that at high frequencies the spatial profile of
the edge current contains oscillations caused by excitation of plasma waves.Comment: 8 pages, 6 figure
Split Dirac cones in HgTe/CdTe quantum wells due to symmetry-enforced level anticrossing at interfaces
We describe the fine structure of Dirac states in HgTe/CdHgTe quantum wells
of critical and close-to-critical thickness and demonstrate the formation of an
anticrossing gap between the tips of the Dirac cones driven by interface
inversion asymmetry. By combining symmetry analysis, atomistic calculations,
and k-p theory with interface terms, we obtain a quantitative description of
the energy spectrum and extract the interface mixing coefficient. The
zero-magnetic-field splitting of Dirac cones can be experimentally revealed in
studying magnetotransport phenomena, cyclotron resonance, Raman scattering, or
THz radiation absorption.Comment: 6 pages, 5 figure
Form factors of the exotic baryons with isospin I=5/2
The electromagnetic form factors of the exotic baryons are calculated in the
framework of the relativistic quark model at small and intermediate momentum
transfer. The charge radii of the E+++ baryons are determined.Comment: 12pages, 2 figure
Phase diagrams of magnetopolariton gases
The magnetic field effect on phase transitions in electrically neutral
bosonic systems is much less studied than those in fermionic systems, such as
superconducting or ferromagnetic phase transitions. Nevertheless, composite
bosons are strongly sensitive to magnetic fields: both their internal structure
and motion as whole particles may be affected. A joint effort of ten
laboratories has been focused on studies of polariton lasers, where
non-equilibrium Bose-Einstein condensates of bosonic quasiparticles,
exciton-polaritons, may appear or disappear under an effect of applied magnetic
fields. Polariton lasers based on pillar or planar microcavities were excited
both optically and electrically. In all cases a pronounced dependence of the
onset to lasing on the magnetic field has been observed. For the sake of
comparison, photon lasing (lasing by an electron-hole plasma) in the presence
of a magnetic field has been studied on the same samples as polariton lasing.
The threshold to photon lasing is essentially governed by the excitonic Mott
transition which appears to be sensitive to magnetic fields too. All the
observed experimental features are qualitatively described within a uniform
model based on coupled diffusion equations for electrons, holes and excitons
and the Gross-Pitaevskii equation for exciton-polariton condensates. Our
research sheds more light on the physics of non-equilibrium Bose-Einstein
condensates and the results manifest high potentiality of polariton lasers for
spin-based quantum logic applications.Comment: 21 pages, 11 figure
Magnetooptical Study of Zeeman Effect in Mn modulation-doped InAs/InGaAs/InAlAs Quantum Well Structures
We report on a magneto-photoluminescence (PL) study of Mn modulation-doped
InAs/InGaAs/InAlAs quantum wells. Two PL lines corresponding to the radiative
recombination of photoelectrons with free and bound-on-Mn holes have been
observed. In the presence of a magnetic field applied in the Faraday geometry
both lines split into two circularly polarized components. While temperature
and magnetic field dependences of the splitting are well described by the
Brillouin function, providing an evidence for exchange interaction with spin
polarized manganese ions, the value of the splitting exceeds the expected value
of the giant Zeeman splitting by two orders of magnitude for a given Mn
density. Possible reasons of this striking observation are discussed
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