168 research outputs found
Direct observation of band-gap closure for a semiconducting carbon nanotube in a large parallel magnetic field
We have investigated the magnetoconductance of semiconducting carbon
nanotubes (CNTs) in pulsed, parallel magnetic fields up to 60 T, and report the
direct observation of the predicted band-gap closure and the reopening of the
gap under variation of the applied magnetic field. We also highlight the
important influence of mechanical strain on the magnetoconductance of the CNTs.Comment: 4 pages, 4 figure
Stacking-order dependent transport properties of trilayer graphene
We report markedly different transport properties of ABA- and ABC-stacked
trilayer graphenes. Our experiments in double-gated trilayer devices provide
evidence that a perpendicular electric field opens an energy gap in the ABC
trilayer, while it causes the increase of a band overlap in the ABA trilayer.
In a perpendicular magnetic field, the ABA trilayer develops quantum Hall
plateaus at filling factors of \nu = 2, 4, 6... with a step of \Delta \nu = 2,
whereas the inversion symmetric ABC trilayer exhibits plateaus at \nu = 6 and
10 with 4-fold spin and valley degeneracy.Comment: 4 pages, 4 figure
Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD
Multi-hadron operators are crucial for reliably extracting the masses of
excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo
calculations. The construction of multi-hadron operators with significant
coupling to the lowest-lying multi-hadron states of interest involves combining
single hadron operators of various momenta. The design and implementation of
large sets of spatially-extended single-hadron operators of definite momentum
and their combinations into two-hadron operators are described. The single
hadron operators are all assemblages of gauge-covariantly-displaced, smeared
quark fields. Group-theoretical projections onto the irreducible
representations of the symmetry group of a cubic spatial lattice are used in
all isospin channels. Tests of these operators on 24^3 x 128 and 32^3 x 256
anisotropic lattices using a stochastic method of treating the low-lying modes
of quark propagation which exploits Laplacian Heaviside quark-field smearing
are presented. The method provides reliable estimates of all needed
correlations, even those that are particularly difficult to compute, such as
eta eta -> eta eta in the scalar channel, which involves the subtraction of a
large vacuum expectation value. A new glueball operator is introduced, and the
evaluation of the mixing of this glueball operator with a quark-antiquark
operator, pi-pi, and eta-eta operators is shown to be feasible.Comment: 20 pages, 7 figures, 21 tables (final version accepted for
publication in Physical Review D
KATANA - a charge-sensitive triggering system for the SRIT experiment
KATANA - the Krakow Array for Triggering with Amplitude discrimiNAtion - has
been built and used as a trigger and veto detector for the SRIT TPC at
RIKEN. Its construction allows operating in magnetic field and providing fast
response for ionizing particles, giving the approximate forward multiplicity
and charge information. Depending on this information, trigger and veto signals
are generated. The article presents performance of the detector and details of
its construction. A simple phenomenological parametrization of the number of
emitted scintillation photons in plastic scintillator is proposed. The effect
of the light output deterioration in the plastic scintillator due to the
in-beam irradiation is discussed.Comment: 14 pages, 11 figure
Determination of energy-dependent neutron backgrounds using shadow bars
Understanding the neutron background is essential for determining the neutron
yield from nuclear reactions. In the analysis presented here, the shadow bars
are placed in front of neutron detectors to determine the energy dependent
neutron background fractions. The measurement of neutron spectra with and
without shadow bars is important to determine the neutron background more
accurately. The neutron background, along with its sources and systematic
uncertainties, are explored with a focus on the impact of background models and
their dependence on neutron energy.Comment: 7 pages, 10 figure
Depth Profiling Photoelectron-Spectroscopic Study of an Organic Spin Valve with a Plasma-Modified Pentacene Spacer
[[abstract]]We report an enhanced magnetoresistance (MR) in an organic spin valve with an oxygen plasma-treated pentacene (PC) spacer. The spin valve containing PC without the treatment shows no MR effect, whereas those with moderately plasma-treated PC exhibit MR ratios up to 1.64% at room temperature. X-ray photoelectron spectroscopy with depth profiling is utilized to characterize the interfacial electronic properties of the plasma-treated PC spacer which shows the formation of a derivative oxide layer. The results suggest an alternative approach to improve the interface quality and in turn to enhance the MR performance in organic spin valves.[[incitationindex]]SCI[[booktype]]電子
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