4,478 research outputs found
Plasmon-phonon coupling in large-area graphene dot and antidot arrays
Nanostructured graphene on SiO2 substrates pave the way for enhanced
light-matter interactions and explorations of strong plasmon-phonon
hybridization in the mid-infrared regime. Unprecedented large-area graphene
nanodot and antidot optical arrays are fabricated by nanosphere lithography,
with structural control down to the sub-100 nanometer regime. The interaction
between graphene plasmon modes and the substrate phonons is experimentally
demonstrated and structural control is used to map out the hybridization of
plasmons and phonons, showing coupling energies of the order 20 meV. Our
findings are further supported by theoretical calculations and numerical
simulations.Comment: 7 pages including 6 figures. Supporting information is available upon
request to author
Room Temperature InP DFB Laser Array Directly Grown on (001) Silicon
Fully exploiting the silicon photonics platform requires a fundamentally new
approach to realize high-performance laser sources that can be integrated
directly using wafer-scale fabrication methods. Direct band gap III-V
semiconductors allow efficient light generation but the large mismatch in
lattice constant, thermal expansion and crystal polarity makes their epitaxial
growth directly on silicon extremely complex. Here, using a selective area
growth technique in confined regions, we surpass this fundamental limit and
demonstrate an optically pumped InP-based distributed feedback (DFB) laser
array grown on (001)-Silicon operating at room temperature and suitable for
wavelength-division-multiplexing applications. The novel epitaxial technology
suppresses threading dislocations and anti-phase boundaries to a less than 20nm
thick layer not affecting the device performance. Using an in-plane laser
cavity defined by standard top-down lithographic patterning together with a
high yield and high uniformity provides scalability and a straightforward path
towards cost-effective co-integration with photonic circuits and III-V FINFET
logic
Plasma Nanoscience: from Nano-Solids in Plasmas to Nano-Plasmas in Solids
The unique plasma-specific features and physical phenomena in the
organization of nanoscale solid-state systems in a broad range of elemental
composition, structure, and dimensionality are critically reviewed. These
effects lead to the possibility to localize and control energy and matter at
nanoscales and to produce self-organized nano-solids with highly unusual and
superior properties. A unifying conceptual framework based on the control of
production, transport, and self-organization of precursor species is introduced
and a variety of plasma-specific non-equilibrium and kinetics-driven phenomena
across the many temporal and spatial scales is explained. When the plasma is
localized to micrometer and nanometer dimensions, new emergent phenomena arise.
The examples range from semiconducting quantum dots and nanowires, chirality
control of single-walled carbon nanotubes, ultra-fine manipulation of
graphenes, nano-diamond, and organic matter, to nano-plasma effects and
nano-plasmas of different states of matter.Comment: This is an essential interdisciplinary reference which can be used by
both advanced and early career researchers as well as in undergraduate
teaching and postgraduate research trainin
Localized states in the conserved Swift-Hohenberg equation with cubic nonlinearity
The conserved Swift-Hohenberg equation with cubic nonlinearity provides the
simplest microscopic description of the thermodynamic transition from a fluid
state to a crystalline state. The resulting phase field crystal model describes
a variety of spatially localized structures, in addition to different spatially
extended periodic structures. The location of these structures in the
temperature versus mean order parameter plane is determined using a combination
of numerical continuation in one dimension and direct numerical simulation in
two and three dimensions. Localized states are found in the region of
thermodynamic coexistence between the homogeneous and structured phases, and
may lie outside of the binodal for these states. The results are related to the
phenomenon of slanted snaking but take the form of standard homoclinic snaking
when the mean order parameter is plotted as a function of the chemical
potential, and are expected to carry over to related models with a conserved
order parameter.Comment: 40 pages, 13 figure
Demagnetization Borne Microscale Skyrmions
Magnetic systems are an exciting realm of study that is being explored on
smaller and smaller scales. One extremely interesting magnetic state that has
gained momentum in recent years is the skyrmionic state. It is characterized by
a vortex where the edge magnetic moments point opposite to the core. Although
skyrmions have many possible realizations, in practice, creating them in a lab
is a difficult task to accomplish. In this work, new methods for skyrmion
generation and customization are suggested. Skyrmionic behavior was numerically
observed in minimally customized simulations of spheres, hemisphere,
ellipsoids, and hemi-ellipsoids, for typ- ical Cobalt parameters, in a range
from approximately 40 nm to 120 nm in diameter simply by applying a field
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