1,373 research outputs found
Rashba interaction in quantum wires with in-plane magnetic fields
We analyze the spectral and transport properties of ballistic quasi
one-dimensional systems in the presence of spin-orbit coupling and in-plane
agnetic fields. Our results demonstrate that Rashba precession and intersubband
coupling must be treated on equal footing for wavevectors near the magnetic
field induced gaps. We find that intersubband coupling limits the occurrence of
negative effective masses at the gap edges and modifies the linear conductance
curves in the strong coupling limit. The effect of the magnetic field on the
spin textured orientation of the wire magnetization is discussed.Comment: 6 pages, 6 figures; new figures, discussion extende
Spin relaxation and anticrossing in quantum dots: Rashba versus Dresselhaus spin-orbit coupling
The spin-orbit splitting of the electron levels in a two-dimensional quantum
dot in a perpendicular magnetic field is studied. It is shown that at the point
of an accidental degeneracy of the two lowest levels above the ground state the
Rashba spin-orbit coupling leads to a level anticrossing and to mixing of
spin-up and spin-down states, whereas there is no mixing of these levels due to
the Dresselhaus term. We calculate the relaxation and decoherence times of the
three lowest levels due to phonons. We find that the spin relaxation rate as a
function of a magnetic field exhibits a cusp-like structure for Rashba but not
for Dresselhaus spin-orbit interaction.Comment: 6 pages, 1 figur
Evanescent states in 2D electron systems with spin-orbit interaction and spin-dependent transmission through a barrier
We find that the total spectrum of electron states in a bounded 2D electron
gas with spin-orbit interaction contains two types of evanescent states lying
in different energy ranges. The first-type states fill in a gap, which opens in
the band of propagating spin-splitted states if tangential momentum is nonzero.
They are described by a pure imaginary wavevector. The states of second type
lie in the forbidden band. They are described by a complex wavevector. These
states give rise to unusual features of the electron transmission through a
lateral potential barrier with spin-orbit interaction, such as an oscillatory
dependence of the tunneling coefficient on the barrier width and electron
energy. But of most interest is the spin polarization of an unpolarized
incident electron flow. Particularly, the transmitted electron current acquires
spin polarization even if the distribution function of incident electrons is
symmetric with respect to the transverse momentum. The polarization efficiency
is an oscillatory function of the barrier width. Spin filtering is most
effective, if the Fermi energy is close to the barrier height.Comment: 9 pages, 9 figures, more general boundary conditions are used, typos
correcte
Efficient electron spin manipulation in a quantum well by an in-plane electric field
Electron spins in a semiconductor quantum well couple to an electric field
{\it via} spin-orbit interaction. We show that the standard spin-orbit coupling
mechanisms can provide extraordinary efficient electron spin manipulation by an
in-plane ac electric field
Interplay of spin-orbit coupling and Zeeman splitting in the absorption lineshape of 2D fermions
We suggest that electron spin resonance (ESR) experiment can be used as a
probe of spinon excitations of hypothetical spin-liquid state of frustrated
antiferromagnet in the presence of asymmetric Dzyaloshinskii-Moriya (DM)
interaction. We describe assumptions under which the ESR response is reduced to
the response of 2D electron gas with Rashba spin-orbit coupling. Unlike
previous treatments, the spin-orbit coupling, \Delta_{SO}, is not assumed small
compared to the Zeeman splitting, \Delta_Z. We demonstrate that ESR response
diverges at the edges of the absorption spectrum for ac magnetic field
perpendicular to the static field. At the compensation point,
\Delta_{SO}\approx \Delta_Z, the broad absorption spectrum exhibits features
that evolve with temperature, T, even when T is comparable to the Fermi energy.Comment: 11 pages, 6 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
Spin-polarized electric currents in quantum transport through tubular two-dimensional electron gases
Scattering theory is employed to derive a Landauer-type formula for the spin
and the charge currents, through a finite region where spin-orbit interactions
are effective. It is shown that the transmission matrix yields the spatial
direction and the magnitude of the spin polarization. This formula is used to
study the currents through a tubular two-dimensional electron gas. In this
cylindrical geometry, which may be realized in experiment, the transverse
conduction channels are not mixed (provided that the spin-orbit coupling is
uniform). It is then found that for modest boundary scattering, each step in
the quantized conductance is split into two, and the new steps have a non-zero
spin conductance, with the spin polarization perpendicular to the direction of
the current.Comment: 6 pages, 5 figure
Spin orbit coupling in bulk ZnO and GaN
Using group theory and Kane-like model together with the
L\"owdining partition method, we derive the expressions of spin-orbit coupling
of electrons and holes, including the linear- Rashba term due to the
intrinsic structure inversion asymmetry and the cubic- Dresselhaus term due
to the bulk inversion asymmetry in wurtzite semiconductors. The coefficients of
the electron and hole Dresselhaus terms of ZnO and GaN in wurtzite structure
and GaN in zinc-blende structure are calculated using the nearest-neighbor
and tight-binding models separately.Comment: 9 pages, 6 figures, to be published in J. Appl. Phy
Anomalous Hall effect in a two-dimensional electron gas with spin-orbit interaction
We discuss the mechanism of anomalous Hall effect related to the contribution
of electron states below the Fermi surface (induced by the Berry phase in
momentum space). Our main calculations are made within a model of
two-dimensional electron gas with spin-orbit interaction of the Rashba type,
taking into account the scattering from impurities. We demonstrate that such an
"intrinsic" mechanism can dominate but there is a competition with the
impurity-scattering mechanism, related to the contribution of states in the
vicinity of Fermi surface. We also show that the contribution to the Hall
conductivity from electron states close to the Fermi surface has the intrinsic
properties as well.Comment: 9 pages, 6 figure
Spin-orbit excitations of quantum wells
Confinement asymmetry effects on the photoabsorption of a quantum well are
discussed by means of a sum-rules approach using a Hamiltonian including a
Rashba spin-orbt coupling. We show that while the strength of the excitation is
zero when the spin-orbit coupling is neglected, the inclusion of the spin-orbit
interaction gives rise to a non zero strength and mean excitation energy in the
far-infrared region. A simple expression for these quantities up to the second
order in the Rashba parameter was derived. The effect of two-body Coulomb
interaction is then studied by means of a Quantum Monte Carlo calculation,
showing that electron-electron correlations induce only a small deviation from
the independent particle model result
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