1,766 research outputs found
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
Resonance-like electrical control of electron spin for microwave measurement
We demonstrate that the spin-polarized electron current can interact with a
microwave electric field in a resonant manner. The spin-orbit interaction gives
rise to an effective magnetic field proportional to the electric current. In
the presence of both dc and ac electric field components, electron spin
resonance occurs if the ac frequency matches with the spin precession frequency
that is controlled by the dc field. In a device consisting of two
spin-polarized contacts connected by a two-dimensional channel, this mechanism
allows electrically tuned detection of the ac signal frequency and amplitude.
For GaAs, such detection is effective in the frequency domain around tens of
gigahertz.Comment: 10 pages, 2 figure
Spin-orbit-induced correlations of the local density of states in two-dimensional electron gas
We study the local density of states (LDOS) of two-dimensional electrons in
the presence of spin-orbit (SO) coupling. Although SO coupling has no effect on
the average density of states, it manifests itself in the correlations of the
LDOS. Namely, the correlation function acquires two satellites centered at
energy difference equal to the SO splitting, , of the electron
Fermi surface. For a smooth disorder the satellites are well separated from the
main peak. Weak Zeeman splitting in a parallel
magnetic field causes an anomaly in the shape of the satellites. We consider
the effect of SO-induced satellites in the LDOS correlations on the shape of
the correlation function of resonant-tunneling conductances at different
source-drain biases, which can be measured experimentally. This shape is
strongly sensitive to the relation between and .Comment: 10 pages, 4 figure
Quantum transport in a curved one-dimensional quantum wire with spin-orbit interactions
The one-dimensional effective Hamiltonian for a planar curvilinear quantum
wire with arbitrary shape is proposed in the presence of the Rashba spin-orbit
interaction. Single electron propagation through a device of two straight lines
conjugated with an arc has been investigated and the analytic expressions of
the reflection and transmission probabilities have been derived. The effects of
the device geometry and the spin-orbit coupling strength on the
reflection and transmission probabilities and the conductance are investigated
in the case of spin polarized electron incidence. We find that no spin-flip
exists in the reflection of the first junction. The reflection probabilities
are mainly influenced by the arc angle and the radius, while the transmission
probabilities are affected by both spin-orbit coupling and the device geometry.
The probabilities and the conductance take the general behavior of oscillation
versus the device geometry parameters and . Especially the electron
transportation varies periodically versus the arc angle . We also
investigate the relationship between the conductance and the electron energy,
and find that electron resonant transmission occurs for certain energy.
Finally, the electron transmission for the incoming electron with arbitrary
state is considered. For the outgoing electron, the polarization ratio is
obtained and the effects of the incoming electron state are discussed. We find
that the outgoing electron state can be spin polarization and reveal the
polarized conditions.Comment: 7 pages, 8 figure
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
Magnetic field effects on spin relaxation in heterostructures
Effect of magnetic field on electron spin relaxation in quantum wells is
studied theoretically. We have shown that Larmor effect and cyclotron motion of
carriers can either jointly suppress D'yakonov-Perel' spin relaxation or
compensate each other. The spin relaxation rates tensor is derived for any
given direction of the external field and arbitrary ratio of bulk and
structural contributions to spin splitting. Our results are applied to the
experiments on electron spin resonance in SiGe heterostructures, and enable us
to extract spin splitting value for such quantum wells.Comment: 6 pages, 4 figure
Spin relaxation in an InAs quantum dot in the presence of terahertz driving fields
The spin relaxation in a 1D InAs quantum dot with the Rashba spin-orbit
coupling under driving THz magnetic fields is investigated by developing the
kinetic equation with the help of the Floquet-Markov theory, which is
generalized to the system with the spin-orbit coupling, to include both the
strong driving field and the electron-phonon scattering. The spin relaxation
time can be effectively prolonged or shortened by the terahertz magnetic field
depending on the frequency and strength of the terahertz magnetic field. The
effect can be understood as the sideband-modulated spin-phonon scattering. This
offers an additional way to manipulate the spin relaxation time.Comment: 8 pages, 1 figure, to be published in PR
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