1,927 research outputs found
Electrical spin injection and accumulation in CoFe/MgO/Ge contacts at room temperature
We first report the all-electrical spin injection and detection in
CoFe/MgO/moderately doped n-Ge contact at room temperature (RT), employing
threeterminal Hanle measurements. A sizable spin signal of ~170 k{\Omega}
{\mu}m^2 has been observed at RT, and the analysis using a single-step
tunneling model gives a spin lifetime of ~120 ps and a spin diffusion length of
~683 nm in Ge. The observed spin signal shows asymmetric bias and temperature
dependences which are strongly related to the asymmetry of the tunneling
process.Comment: 28 pages, 5 figure
Doping-tunable thermal emission from plasmon polaritons in semiconductor epsilon-near-zero thin films
We utilize the unique dispersion properties of leaky plasmon polaritons in epsilon-near-zero (ENZ) thin films to demonstrate thermal radiation control. Owing to its highly flat dispersion above the light line, a thermally excited leaky wave at the ENZ frequency out-couples into free space without any scattering structures, resulting in a narrowband, wide-angle, p-polarized thermal emission spectrum. We demonstrate this idea by measuring angle-and polarization-resolved thermal emission spectra from a single layer of unpatterned, doped semiconductors with deep-subwavelength film thickness (d/lambda(0) similar to 6 x 10(-3), where d is the film thickness and lambda(0) is the free space wavelength). We show that this semiconductor ENZ film effectively works as a leaky wave thermal radiation antenna, which generates far-field radiation from a thermally excited mode. The use of semiconductors makes the radiation frequency highly tunable by controlling doping densities and also facilitates device integration with other components. Therefore, this leaky plasmon polariton emission from semiconductor ENZ films provides an avenue for on-chip control of thermal radiation. (C) 2014 AIP Publishing LLCopen0
The Globular Cluster System of M60 (NGC 4649). I. CFHT MOS Spectroscopy and Database
We present the measurement of radial velocities for globular clusters in M60,
giant elliptical galaxy in the Virgo cluster. Target globular cluster
candidates were selected using the Washington photometry based on the deep
16\arcmin \times 16\arcmin images taken at the KPNO 4m and using the
photometry derived from the HST/WFPC2 archive images. The spectra of the target
objects were obtained using the Multi-Object Spectrograph (MOS) at the
Canada-France-Hawaii Telescope (CFHT). We have measured the radial velocity for
111 objects in the field of M60: 93 globular clusters (72 blue globular
clusters with and 21 red globular clusters with
), 11 foreground stars, 6 small galaxies, and the nucleus of
M60. The measured velocities of the 93 globular clusters range from
km s to km s, with a mean value of
km s, which is in good agreement with the velocity of the nucleus of M60
( km s). Combining our results with data in the
literature, we present a master catalog of radial velocities for 121 globular
clusters in M60. The velocity dispersion of the globular clusters in the master
catalog is found to be km s for the entire sample,
km s for 83 blue globular clusters, and
km s for 38 red globular clusters.Comment: 29 pages, 8 figures. To appear in Ap
Deterministic creation and deletion of a single magnetic skyrmion observed by direct time-resolved X-ray microscopy
Spintronic devices based on magnetic skyrmions are a promising candidate for
next-generation memory applications due to their nanometre-size,
topologically-protected stability and efficient current-driven dynamics. Since
the recent discovery of room-temperature magnetic skyrmions, there have been
reports of current-driven skyrmion displacement on magnetic tracks and
demonstrations of current pulse-driven skyrmion generation. However, the
controlled annihilation of a single skyrmion at room temperature has remained
elusive. Here we demonstrate the deterministic writing and deleting of single
isolated skyrmions at room temperature in ferrimagnetic GdFeCo films with a
device-compatible stripline geometry. The process is driven by the application
of current pulses, which induce spin-orbit torques, and is directly observed
using a time resolved nanoscale X-ray imaging technique. We provide a
current-pulse profile for the efficient and deterministic writing and deleting
process. Using micromagnetic simulations, we also reveal the microscopic
mechanism of the topological fluctuations that occur during this process.Comment: 27 pages, 4 figure
Chiral electroluminescence from thin-film perovskite metacavities
Chiral light sources realized in ultracompact device platforms are highly
desirable for various applications. Among active media employed for thin-film
emission devices, lead-halide perovskites have been extensively studied for
photoluminescence due to their exceptional properties. However, up to date,
there have been no demonstrations of chiral electroluminescence with a
substantial degree of circular polarization (DCP), being critical for the
development of practical devices. Here, we propose a new concept of chiral
light sources based on a thin-film perovskite metacavity and experimentally
demonstrate chiral electroluminescence with DCP approaching 0.38. We design a
metacavity created by a metal and a dielectric metasurface supporting photonic
eigenstates with close-to-maximum chiral response. Chiral cavity modes
facilitate asymmetric electroluminescence of pairs of left and right circularly
polarized waves propagating in the opposite oblique directions. The proposed
ultracompact light sources are especially advantageous for many applications
requiring chiral light beams of both helicities.Comment: 20 pages, 4 figure
PECTINASE-MODIFIED RED GINSENG (GS-E3D) INHIBIT NF-ΚB TRANSLOCATION AND NITRIC OXIDE PRODUCTION IN LIPOPOLYSACCHARIDE-STIMULATED RAW 264.7 CELLS
Objective: Red ginseng has been used as traditional medicines and functional foods in the world, because of its health benefits. The aim of this study was to elucidate the anti-inflammatory effect and mechanism of pectinase-modified red ginseng (GS-E3D) with a cellular model of lipopolysaccharide (LPS)-stimulated RAW264.7 cells.Methods: To study the anti-inflammatory effect of GS-E3D, the key inflammation mediators such as nitric oxide (NO),prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), Cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF-α), and interleukin (IL)-6 production as well as on nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) activation, were measured by using the enzyme linked immunosorbent assay (ELISA)and Western blotting.Results: GS-E3D potently inhibited TNF-α and IL-6 and also diminished NO over-production, which was accompanied by the down-regulation of iNOS expression. GS-E3D effectively suppressed LPS-induced NF-κB activation through inhibiting the hyper-phosphorylation and degradation of IκB-α and phosphorylation of p38, ERK1/2 and JNK in MAPK signaling pathway.Conclusion: GS-E3D has a potential to be as an anti-inflammatory agent for functional food or cosmetic materials targeting on the NF-κB p65 and MAPKs signaling pathways.Â
Mesoscopic Luttinger Liquid Theory in an Aharonov-Bohm Ring
A careful study on the mesoscopic PC in a Luttinger liquid ring is carried
out.
It is shown that discreteness plays an important role in calculating the PC
caused by the magnetic flux. At zero temperature, the current is shown to be
independent of the interaction even when is not zero. The current
becomes enhanced at finite temperatures comparing to the non-interacting case,
when the parameter g is positive.Comment: 4 pages, 2 figures. Version to appear in PR
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