460 research outputs found

### Theory of spin-Hall transport of heavy holes in semiconductor quantum wells

Based on a proper definition of the spin current, we investigate the
spin-Hall effect of heavy holes in narrow quantum wells in the presence of
Rashba spin-orbit coupling by using a spin-density matrix approach. In contrast
to previous results obtained on the basis of the conventional definition of the
spin current, we arrive at the conclusion that an electric-field-induced
steady-state spin-Hall current does not exist in both, pure and disordered
infinite samples. Only an ac field can induce a spin-Hall effect in such
systems.Comment: 6 pages, submitted to J. Phys.: Condens. Matte

### Excitation of spin waves on a cylindrical semiconductor heterostructure with Rashba spin-orbit interaction

Elementary excitations in a paramagnetic semiconductor quantum well confined
to a cylindrical surface are theoretically studied on the basis of coupled
spin-charge drift-diffusion equations. The electric-field-mediated eigenmodes
are optically excited by an oscillating interference pattern, which induces a
current in the outer circuit. For a cylinder with a given radius, sharp
resonances are predicted to occur in the steady-state current response, which
are due to weakly damped spin remagnetization waves.Comment: 7 pages, 1figur

### Spin-Hall effect and spin-coherent excitations in a strongly confined two-dimensional hole gas

Based on a rigorous quantum-kinetic approach, spin-charge coupled
drift-diffusion equations are derived for a strongly confined two-dimensional
hole gas. An electric field leads to a coupling between the spin and charge
degrees of freedom. For weak spin-orbit interaction, this coupling gives rise
to the intrinsic spin-Hall effect. There exists a threshold value of the
spin-orbit coupling constant that separates spin diffusion from ballistic spin
transport. In the latter regime, undamped spin-coherent oscillations are
observed. This result is confirmed by an exact microscopic approach valid in
the ballistic regime.Comment: 10 pages, 2 figure

### Coupled spin-charge drift-diffusion approach for a two-dimensional electron gas with Rashba spin-orbit coupling

Based on kinetic equations for the density matrix, drift-diffusion equations
are derived for a two-dimensional electron gas with Rashba spin-orbit coupling.
Universal results are obtained for the weak coupling case. Most interesting is
the observation that with increasing spin-orbit coupling strengths there is a
sharp transition between spin diffusion and ballistic spin transport. For
strong spin-orbit coupling, when the elastic scattering time is much larger
than the spin relaxation time, undamped spin-coherent waves are identified. The
existence of these long-lived spin-coherent states is confirmed by exact
analytical results obtained from microscopic kinetic equations valid in the
ballistic regime.Comment: 16 pages, 3 figure

### Effects of impurity scattering on electron-phonon resonances in semiconductor superlattice high-field transport

A non-equilibrium Green's function method is applied to model high-field
quantum transport and electron-phonon resonances in semiconductor
superlattices. The field-dependent density of states for elastic (impurity)
scattering is found non-perturbatively in an approach which can be applied to
both high and low electric fields. I-V curves, and specifically electron-phonon
resonances, are calculated by treating the inelastic (LO phonon) scattering
perturbatively. Calculations show how strong impurity scattering suppresses the
electron-phonon resonance peaks in I-V curves, and their detailed sensitivity
to the size, strength and concentration of impurities.Comment: 7 figures, 1 tabl

### Field-induced spin excitations in Rashba-Dresselhaus two-dimensional electron systems probed by surface acoustic waves

A spin-rotation symmetry in spin-orbit coupled two-dimensional electron
systems gives rise to a long-lived spin excitation that is robust against
short-range impurity scattering. The influence of a constant in-plane electric
field on this persistent spin helix is studied. To probe the field-induced
eigen-modes of the spin-charge coupled system, a surface acoustic wave is
exploited that provides the wave-vector for resonant excitation. The approach
takes advantage of methods worked out in the field of space-charge waves. Sharp
resonances in the field dependence of the in-plane and out-of-plane
magnetization are identified.Comment: 13 pages, 2 figure

### Current-induced spin polarization for a general two-dimensional electron system

In this paper, current-induced spin polarization for two-dimensional electron
gas with a general spin-orbit interaction is investigated. For isotropic energy
spectrum, the in-plane current-induced spin polarization is found to be
dependent on the electron density for non-linear spin-orbit interaction and
increases with the increment of sheet density, in contrast to the case for $\bm
k$-linear spin-orbit coupling model. The numerical evaluation is performed for
InAs/InSb heterojunction with spin-orbit coupling of both linear and cubic
spin-orbit coupling types. For $\delta$-type short-range electron-impurity
scattering, it is found that the current-induced spin polarization increases
with increasing the density when cubic spin-orbit couplings are considered.
However, for remote disorders, a rapid enhancement of current-induced spin
polarization is always observed at high electron density, even in the case
without cubic spin-orbit coupling. This result demonstrates the
collision-related feature of current-induced spin polarization. The effects of
different high order spin-orbit couplings on spin polarization can be
comparable.Comment: 5 pages, 3 figure

### What Writing Assistants Can Learn from Programming IDEs

With the development of artificial intelligence, writing assistants (WAs) are
changing the way people interact with text, creating lengthy outputs that can
be overwhelming for users. The programming field has long addressed this issue,
and Integrated Development Environments (IDEs) have been created for efficient
software development, helping programmers reduce the cognitive load. This
experience could be employed in the development of WAs. IDEs can also be used
to test assumptions about interventions that help people interact with WAs
efficiently. Previous works have successfully used self-written IDE plugins to
test hypotheses in the field of human-computer interaction. The lessons learned
can be applied to the building of WAs.Comment: Accepted to the In2Writing Workshop co-located with CHI 2023, 2 page

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