390 research outputs found
Spin-Wave Relaxation in a Quantum Hall Ferromagnet
We study spin wave relaxation in quantum Hall ferromagnet regimes. Spin-orbit
coupling is considered as a factor determining spin nonconservation, and
external random potential as a cause of energy dissipation making spin-flip
processes irreversible. We compare this relaxation mechanism with other
relaxation channels existing in a quantum Hall ferromagnet.Comment: Submitted to JETP Letter
Goldstone Mode Relaxation in a Quantum Hall Ferromagnet due to Hyperfine Interaction with Nuclei
Spin relaxation in quantum Hall ferromagnet regimes is studied. As the
initial non-equilibrium state, a coherent deviation of the spin system from the
direction is considered and the breakdown of this Goldstone-mode
state due to hyperfine coupling to nuclei is analyzed. The relaxation occurring
non-exponentially with time is studied in terms of annihilation processes in
the "Goldstone condensate" formed by "zero spin excitons". The relaxation rate
is calculated analytically even if the initial deviation is not small. This
relaxation channel competes with the relaxation mechanisms due to spin-orbit
coupling, and at strong magnetic fields it becomes dominating.Comment: 8 page
Bound States in a Quantized Hall Ferromagnet
We report on a study of the quasielectron-quasihole and skyrmion-antiskyrmion
bound states in the quantum Hall regime. The short range attraction
potential is assumed to be determined by a point magnetic impurity. The
calculations are performed within the strong field approximation when the
binding energy and the characteristic electron-electron interaction energy are
smaller than the Landau level spacing. The Excitonic Representation technique
is used in that case.Comment: 8 page
The Cyclotron Spin-Flip Mode as the Lowest-Energy Excitation of Unpolarized Integer Quantum Hall States
The cyclotron spin-flip modes of spin unpolarized integer quantum Hall states
() have been studied with inelastic light scattering. The energy of
these modes is significantly smaller compared to the bare cyclotron gap. Second
order exchange corrections are held responsible for a negative energy
contribution and render these modes the lowest energy excitations of
unpolarized integer quantum Hall states.Comment: Published: Phys. Rev. B 72, 073304 (2005
Spin relaxation in a two-electron quantum dot
We discuss the rate of relaxation of the total spin in the two-electron
droplet in the vicinity of the magnetic field driven singlet-triplet
transition. The total spin relaxation is attributed to spin-orbit and
electron-phonon interactions. The relaxation process is found to depend on the
spin of ground and excited states. This asymmetry is used to explain puzzles in
recent high source-drain transport experiments.Comment: 9 pages in the PDF format, 1 figur
Impact of system parameter selection on radar sensor performance in automotive applications
The paper deals with the investigation of relevant boundary conditions to be
considered in order to operate 77/79 GHz narrow and ultra wide band
automotive radar sensors in the automotive platform and the automotive
environment
Simplified modeling of EM field coupling to complex cable bundles
In this contribution, the procedure "Equivalent Cable Bundle Method" is
used for the simplification of large cable bundles, and it is extended to the
application on differential signal lines. The main focus is on the reduction
of twisted-pair cables. Furthermore, the process presented here allows to
take into account cables with wires that are situated quite close to each
other. The procedure is based on a new approach to calculate the geometry of
the simplified cable and uses the fact that the line parameters do not
uniquely correspond to a certain geometry. For this reason, an optimization
algorithm is applied
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