9,697 research outputs found
A theory of hyperfinite sets
We develop an axiomatic set theory -- the Theory of Hyperfinite Sets THS,
which is based on the idea of existence of proper subclasses of big finite
sets. We demonstrate how theorems of classical continuous mathematics can be
transfered to THS, prove consistency of THS and present some applications.Comment: 28 page
Magnetoconductance of carbon nanotube p-n junctions
The magnetoconductance of p-n junctions formed in clean single wall carbon
nanotubes is studied in the noninteracting electron approximation and
perturbatively in electron-electron interaction, in the geometry where a
magnetic field is along the tube axis. For long junctions the low temperature
magnetoconductance is anomalously large: the relative change in the conductance
becomes of order unity even when the flux through the tube is much smaller than
the flux quantum. The magnetoconductance is negative for metallic tubes. For
semiconducting and small gap tubes the magnetoconductance is nonmonotonic;
positive at small and negative at large fields.Comment: 5 pages, 2 figure
Novel relativistic plasma excitations in a gated two-dimensional electron system
The microwave response of a two-dimensional electron system (2DES) covered by
a conducting top gate is investigated in the relativistic regime for which the
2D conductivity . Weakly damped plasma waves are
excited in the gated region of the 2DES. The frequency and amplitude of the
resulting plasma excitations show a very unusual dependence on the magnetic
field, conductivity, gate geometry and separation from the 2DES. We show that
such relativistic plasmons survive for temperatures up to 300 K, allowing for
new room-temperature microwave and terahertz applications.Comment: 9 pages, 7 figure
Re-entrant localization of single particle transport in disordered Andreev wires
We study effects of disorder on the low energy single particle transport in a
normal wire surrounded by a superconductor. We show that the heat conductance
includes the Andreev diffusion decreasing with increase in the mean free path
and the diffusive drift produced by a small particle-hole asymmetry,
which increases with increasing . The conductance thus has a minimum as a
function of which leads to a peculiar re-entrant localization as a
function of the mean free path.Comment: 4 pages, 2 figure
Two-photon correlations as a sign of sharp transition in quark-gluon plasma
The photon production arising due to time variation of the medium has been
considered. The Hamilton formalism for photons in time-variable medium (plasma)
has been developed with application to inclusive photon production. The results
have been used for calculation of the photon production in the course of
transition from quark-gluon phase to hadronic phase in relativistic heavy ion
collisions. The relative strength of the effect as well as specific two- photon
correlations have been evaluated. It has been demonstrated that the opposite
side two-photon correlations are indicative of the sharp transition from the
quark-gluon phase to hadrons.Comment: 23 pages, 2 figure
Nonlinear Hysteretic Torsional Waves
We theoretically study and experimentally report the propagation of nonlinear
hysteretic torsional pulses in a vertical granular chain made of cm-scale,
self-hanged magnetic beads. As predicted by contact mechanics, the torsional
coupling between two beads is found nonlinear hysteretic. This results in a
nonlinear pulse distortion essentially different from the distortion predicted
by classical nonlinearities, and in a complex dynamic response depending on the
history of the wave particle angular velocity. Both are consistent with the
predictions of purely hysteretic nonlinear elasticity and the
Preisach-Mayergoyz hysteresis model, providing the opportunity to study the
phenomenon of nonlinear dynamic hysteresis in the absence of other type of
material nonlinearities. The proposed configuration reveals a plethora of
interesting phenomena including giant amplitude-dependent attenuation, short
term memory as well as dispersive properties. Thus, it could find interesting
applications in nonlinear wave control devices such as strong
amplitude-dependent filters
Tunneling into d-wave superconductors: Effects of interface spin-orbit coupling
Tunneling conductance of a clean normal metal/d-wave superconductor junction
is studied by using the extended Blonder-Tinkham-Klapwijk formalism. We show
that the conductance is significantly affected by the interface spin-orbit
coupling of the Rashba type, which is inevitably present due to the asymmetry
of the junction.Comment: 4 pages, 4 figure
Simple theory of extremely overdoped HTS
We demonstrate the existence of a simple physical picture of
superconductivity for extremely overdoped CuO2 planes. It possesses all
characteristic features of HTS, such as a high superconducting transition
temperature, the symmetry of order parameter, and the
coexistence of a single electron Fermi surface and a pseudogap in the normal
state. Values of pseudogap are calculated for different doping levels. An
orbital paramagnetism of preformed pairs is predicted.Comment: 7 pages, 1 figur
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