33,107 research outputs found
Enhanced visibility of graphene: effect of one-dimensional photonic crystal
We investigate theoretically the light reflectance of a graphene layer
prepared on the top of one-dimensional Si/SiO2 photonic crystal (1DPC). It is
shown that the visibility of the graphene layers is enhanced greatly when 1DPC
is added, and the visibility can be tuned by changing the incident angle and
light wavelengths. This phenomenon is caused by the absorption of the graphene
layer and the enhanced reflectance of the 1DPC.Comment: 4 pages, 4 figures. published, ApplPhysLett_91_18190
Tests of a Novel Design of Resistive Plate Chambers
A novel design of Resistive Plate Chambers (RPCs), using only a single
resistive plate, is being proposed. Based on this design, two large size
prototype chambers were constructed and were tested with cosmic rays and in
particle beams. The tests confirmed the viability of this new approach. In
addition to showing an improved single-particle response compared to the
traditional 2-plate design, the novel chambers also prove to be suitable for
calorimetric applications
Large exchange bias after zero-field cooling from an unmagnetized state
Exchange bias (EB) is usually observed in systems with interface between
different magnetic phases after field cooling. Here we report an unusual
phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after
zero-field cooling from an unmagnetized state. We propose this is related to
the newly formed interface between different magnetic phases during the initial
magnetization process. The magnetic unidirectional anisotropy, which is the
origin of EB effect, can be created isothermally below the blocking
temperature.Comment: including supplementary information, Accepted by Physical Review
Letter
Coarse-grained microscopic model of glass formers
We introduce a coarse-grained model for atomic glass formers. Its elements
are physically motivated local microscopic dynamical rules parameterized by
observables. Results of the model are established and used to interpret the
measured behaviors of supercooled fluids approaching glass transitions. The
model predicts the presence of a crossover from hierarchical super-Arrhenius
dynamics at short length scales to diffusive Arrhenius dynamics at large length
scales. This prediction distinguishes our model from other theories of glass
formers and can be tested by experiment.Comment: 5 pages, 5 figure
Simulation of the Burridge-Knopoff Model of Earthquakes with Variable Range Stress Transfer
Simple models of earthquake faults are important for understanding the
mechanisms for their observed behavior, such as Gutenberg-Richter scaling and
the relation between large and small events, which is the basis for various
forecasting methods. Although cellular automaton models have been studied
extensively in the long-range stress transfer limit, this limit has not been
studied for the Burridge-Knopoff model, which includes more realistic friction
forces and inertia. We find that the latter model with long-range stress
transfer exhibits qualitatively different behavior than both the long-range
cellular automaton models and the usual Burridge-Knopoff model with nearest
neighbor springs, depending on the nature of the velocity-weakening friction
force. This result has important implications for our understanding of
earthquakes and other driven dissipative systems.Comment: 4 pages, 5 figures, published on Phys. Rev. Let
Momentum Distribution of Near-Zero-Energy Photoelectrons in the Strong-Field Tunneling Ionization in the Long Wavelength Limit
We investigate the ionization dynamics of Argon atoms irradiated by an
ultrashort intense laser of a wavelength up to 3100 nm, addressing the momentum
distribution of the photoelectrons with near-zero-energy. We find a surprising
accumulation in the momentum distribution corresponding to meV energy and a
\textquotedblleft V"-like structure at the slightly larger transverse momenta.
Semiclassical simulations indicate the crucial role of the Coulomb attraction
between the escaping electron and the remaining ion at extremely large
distance. Tracing back classical trajectories, we find the tunneling electrons
born in a certain window of the field phase and transverse velocity are
responsible for the striking accumulation. Our theoretical results are
consistent with recent meV-resolved high-precision measurements.Comment: 5 pages, 4 figure
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