4,577 research outputs found
Electric-Field-Induced Resonant Spin Polarization in a Two-Dimensional Electron Gas
Electric response of spin polarization in two-dimensional electron gas with
structural inversion asymmetry subjected to a magnetic field was studied by
means of the linear and non-linear theory and numerical simulation with the
disorder effect. It was found by Kubo linear reponse theory that an electric
resonant response of spin polarization occurs when the Fermi surface is located
near the crossing of two Landau levels, which is induced from the competition
between the spin-orbit coupling and Zeeman splitting. The scaling behavior was
investigated with a simplified two-level model by non-linear method, and the
resonant peak value is reciprocally proportional to the electric field at low
temperatures and to temperature for finite electric fields. Finally numerical
simulation illustrated that impurity potential opens an enegy gap near the
resonant point and suppresses the effect gradually with the increasing strength
of disorder. This resonant effect may provide an efficient way to control spin
polarization by an external electric field.Comment: 6 pages, 5 figure
The catalogues and mid-infrared environment of Interstellar OH Masers
Data for a number of OH maser lines have been collected from surveys. The
posi- tions are compared to recent mid-infrared (MIR) surveys such as
Spitzer-GLIMPSE and WISE, restricting the comparison to point sources. The
colors and intensities of the IR sources are compared. There are many 18 cm OH
masers, but far fewer in lines arising from higher energy levels. We also make
a comparison with the 5 cm Class II methanol masers. We have divided the
results into 3 subsamples: those associated with OH masers only, those
associated with OH masers and Class II methanol masers, and those only
associated with Class II methanol masers. There are no obvious dif- ferences in
the color-color or color-magnitude results for the GLIMPSE point sources.
However, according to the results from the WISE 22 {\mu}m survey, the sources
associ- ated with OH masers are brighter than those associated with methanol
masers. We interpret the presence of OH and methanol masers mark the locations
of regions where stars are forming. The OH masers are located on the borders of
sharp features found in the IR. These are referred to as bubbles. If the OH
masers mark the positions of protostars, the result provides indirect evidence
for triggered star formation caused by the expansion of the bubbles.Comment: 23 pages (11 pages online only), 12 figures, Accepted. Monthly
Notices of the Royal Astronomical Society,201
- …