14,273 research outputs found
A Mini Immersed Finite Element Method for Two-Phase Stokes Problems on Cartesian Meshes
This paper presents a mini immersed finite element (IFE) method for solving
two- and three-dimensional two-phase Stokes problems on Cartesian meshes. The
IFE space is constructed from the conventional mini element with shape
functions modified on interface elements according to interface jump
conditions, while keeping the degrees of freedom unchanged. Both discontinuous
viscosity coefficients and surface forces are considered in the construction.
The interface is approximated via discrete level set functions and explicit
formulas of IFE basis functions and correction functions are derived, which
make the IFE method easy to implement. The optimal approximation capabilities
of the IFE space and the inf-sup stability and the optimal a priori error
estimate of the IFE method are derived rigorously with constants independent of
the mesh size and how the interface cuts the mesh. It is also proved that the
condition number has the usual bound independent of the interface. Numerical
experiments are provided to confirm the theoretical results
Observation of electric current induced by optically injected spin current
A normally incident light of linear polarization injects a pure spin current
in a strip of 2-dimensional electron gas with spin-orbit coupling. We report
observation of an electric current with a butterfly-like pattern induced by
such a light shed on the vicinity of a crossbar shaped InGaAs/InAlAs quantum
well. Its light polarization dependence is the same as that of the spin
current. We attribute the observed electric current to be converted from the
optically injected spin current caused by scatterings near the crossing. Our
observation provides a realistic technique to detect spin currents, and opens a
new route to study the spin-related science and engineering in semiconductors.Comment: 15 pages, 4 figure
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