734 research outputs found
Thermal stability and oxidation of layer-structured rhombohedral In3Se4 nanostructures
The thermal stability and oxidation of layer-structured rhombohedral In3Se4 nanostructures have been investigated. In-situ synchrotron X-ray diffraction in a sealed system reveals that In3Se4 has good thermal stability up to 900 degrees C. In contrast, In3Se4 has lower thermal stability up to 550 or 200 degrees C when heated in an atmosphere flushed with Ar or in air, respectively. The degradation mechanism was determined to be the oxidation of In3Se4 by O-2 in the heating environment. This research demonstrates how thermal processing conditions can influence the thermal stability of In3Se4, suggesting that appropriate heating environment for preserving its structural integrity is required. (C) 2013 AIP Publishing LLC
Extending the Propagation Distance of a Silver Nanowire Plasmonic Waveguide with a Dielectric Multilayer Substrate
Chemical synthesized silver nanowires have been proved to be the efficient
architecture for Plasmonic waveguides, but the high propagation loss prevents
their widely applications. Here, we demonstrate that the propagation distance
of the plasmons along the Ag NW can be extended if the Ag NW was placed on a
dielectric multilayer substrate containing a photonic band gap, but not placed
on a commonly used glass substrate. The propagation distance at 630 nm
wavelength can reach 16 um even that the Ag NW is as thin as 90 nm in diameter.
Experimental and simulation results further show that the polarization of this
propagating plasmon mode was nearly parallel to the surface of the dielectric
multilayer, so it was excited by a transverse-electric polarized Bloch surface
wave propagating along a polymer nanowire with diameter at only about 170 nm on
the same dielectric multilayer. Numerical simulations were also carried out and
consistent with the experiment results. Our work provides a platform to extend
the propagation distance of plasmonic waveguide and also for the integration
between photonic and plasmonic waveguides on the nanometre scale.Comment: 5 pages, 4 figure
Magnetotransport properties of Cd3As2 nanostructures
Three-dimensional (3D) topological Dirac semimetal is a new kind of material
that has a linear energy dispersion in 3D momentum space and can be viewed as
an analog of graphene. Extensive efforts have been devoted to the understanding
of bulk materials, but yet it remains a challenge to explore the intriguing
physics in low-dimensional Dirac semimetals. Here, we report on the synthesis
of Cd3As2 nanowires and nanobelts and a systematic investigation of their
magnetotransport properties. Temperature-dependent ambipolar behavior is
evidently demonstrated, suggesting the presence of finite-size of bandgap in
nanowires. Cd3As2 nanobelts, however, exhibit metallic characteristics with a
high carrier mobility exceeding 32,000 cm2V-1s-1 and pronounced anomalous
double-period Shubnikov-de Haas (SdH) oscillations. Unlike the bulk
counterpart, the Cd3As2 nanobelts reveal the possibility of unusual change of
the Fermi sphere owing to the suppression of the dimensionality. More
importantly, their SdH oscillations can be effectively tuned by the gate
voltage. The successful synthesis of Cd3As2 nanostructures and their rich
physics open up exciting nanoelectronic applications of 3D Dirac semimetals.Comment: 18 pages, 5 figure
Dimensionality-confined superconductivity within SrNbO3-SrTiO3 heterostructures
Interfaces between transition-metal oxides are able to host two-dimensional
electron gases (2DEGs) and exhibit exotic quantum phenomena. Here we report the
observation of superconductivity below 230 mK for the heterostructure composed
of SrNbO3 (SNO) and SrTiO3 (STO). Different from some other counterparts with
two insulators, the metallic SNO provides a novel mechanism to form a quasi
2DEG by charge transfer from bulk towards interface under strain. The
superconductivity, residing within the strained SNO layer near the interface,
is contributed by an electron system with record-low carrier density. Notably,
although embedded in a normal metallic layer with a carrier density 4 to 5
orders higher, the electron system is still uniquely well-protected to retain
high mobility and lies deep in extreme quantum regime
A new crystal: Layer-structured rhombohedral In3Se4
A new layer-structured rhombohedral In3Se4 crystal was synthesized by a facile and mild solvothermal method. Detailed structural and chemical characterizations using transmission electron microscopy, coupled with synchrotron X-ray diffraction analysis and Rietveld refinement, indicate that In3Se4 crystallizes in a layered rhombohedral structure with lattice parameters of a = 3.964 ± 0.002 Å and c = 39.59 ± 0.02 Å, a space group of R3m, and with a layer composition of Se-In-Se-In-Se-In-Se. The theoretical modeling and experimental measurements indicate that the In3Se4 is a self-doped n-type semiconductor. This study not only enriches the understanding on crystallography of indium selenide crystals, but also paves a way in the search for new semiconducting compounds. This journal i
Landau level splitting in Cd3As2 under high magnetic fields
Three-dimensional topological Dirac semimetals (TDSs) are a new kind of Dirac
materials that exhibit linear energy dispersion in the bulk and can be viewed
as three-dimensional graphene. It has been proposed that TDSs can be driven to
other exotic phases like Weyl semimetals, topological insulators and
topological superconductors by breaking certain symmetries. Here we report the
first transport experiment on Landau level splitting in TDS Cd3As2 single
crystals under high magnetic fields, suggesting the removal of spin degeneracy
by breaking time reversal symmetry. The detected Berry phase develops an
evident angular dependence and possesses a crossover from nontrivial to trivial
state under high magnetic fields, a strong hint for a fierce competition
between the orbit-coupled field strength and the field-generated mass term. Our
results unveil the important role of symmetry breaking in TDSs and further
demonstrate a feasible path to generate a Weyl semimetal phase by breaking time
reversal symmetry.Comment: 31 page
Dynamically generated 0^+ heavy mesons in a heavy chiral unitary approach
In terms of the heavy chiral Lagrangian and the unitarized coupled-channel
scattering amplitude, interaction between the heavy meson and the light
pseudoscalar meson is studied. By looking for the pole of scattering matrix on
an appropriate Riemann sheet, a bound state with the mass of
GeV is found. This state can be associated as the narrow
state found recently. In the same way, a bound
state is found, and its mass of GeV is predicted.
The spectra of and with are further investigated. One
broad and one narrow states are predicted in both charm and bottom sectors. The
coupling constants and decay widths of the predicted states are also
calculated.Comment: 15 pages, 1 figure. One numerical error in Eq.16 correcte
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