2,024 research outputs found
Landau level mixing by full spin-orbit interactions
We study a two-dimensional electron gas in a perpendicular magnetic field in
the presence of both Rashba and Dresselhaus spin-orbit interactions. Using a
Bogoliubov transformation we are able to write an approximate formula for the
Landau levels, thanks to the simpler form of the resulting Hamiltonian. The
exact numerical calculation of the energy levels, is also made simpler by our
formulation. The approximate formula and the exact numerical results show
excellent agreement for typical semiconductors, especially at high magnetic
fields. We also show how effective Zeeman coupling is modified by spin-orbit
interactions.Comment: 5 pages, 5 figure
Nonlocal Spin Transport as a Probe of Viscous Magnon Fluids
Magnons in ferromagnets behave as a viscous fluid over a length scale, the
momentum-relaxation length, below which momentum-conserving scattering
processes dominate. We show theoretically that in this hydrodynamic regime
viscous effects lead to a sign change in the magnon chemical potential, which
can be detected as a sign change in the nonlocal resistance measured in spin
transport experiments. This sign change is observable when the
injector-detector distance becomes comparable to the momentum-relaxation
length. Taking into account momentum- and spin-relaxation processes, we
consider the quasiconservation laws for momentum and spin in a magnon fluid.
The resulting equations are solved for nonlocal spin transport devices in which
spin is injected and detected via metallic leads. Because of the finite
viscosity we also find a backflow of magnons close to the injector lead. Our
work shows that nonlocal magnon spin transport devices are an attractive
platform to develop and study magnon-fluid dynamics
Search for the Higgs Boson at LHC in 3-3-1 Model
We present an analysis of production and signature of neutral Higgs boson
() on the version of the 3-3-1 model containing heavy leptons at the
Large Hadron Collider. We studied the possibility to identify it using the
respective branching ratios. Cross section are given for the collider energy,
14 TeV. Event rates and significances are discussed for two
possible values of integrated luminosity, 300 fb and 3000 fb.Comment: 17 pages 7 figures. arXiv admin note: substantial text overlap with
arXiv:1205.404
Spatial correlations in chaotic nanoscale systems with spin-orbit coupling
We investigate the statistical properties of wave functions in chaotic
nanostructures with spin-orbit coupling (SOC), focussing in particular on
spatial correlations of eigenfunctions. Numerical results from a microscopic
model are compared with results from random matrix theory in the crossover from
the gaussian orthogonal to the gaussian symplectic ensembles (with increasing
SOC); one- and two-point distribution functions were computed to understand the
properties of eigenfunctions in this crossover. It is found that correlations
of wave function amplitudes are suppressed with SOC; nevertheless,
eigenfunction correlations play a more important role in the two-point
distribution function(s), compared to the case with vanishing SOC. Experimental
consequences of our results are discussed.Comment: Submitted to PR
Human Identities and Nation Building: Comparative Analysis, Markets, and the Modern University
The purpose of this article is to discuss the dilemma of the multi-university in sustainable education, research, and outreach by addressing some of the ways in which universities, must generate actions that seek to address these challenges, develop strategic relationships, and maximize their potential in the areas of teaching, research and service to society. Significantly, we examine how sustainability is experienced by nations—in our case Mexico—by analyzing higher education and its mission in developing citizens and economic sovereignty. The author’s goal is to establish a new paradigm by which practitioners and researchers can collaborate to produce the ideas that stimulate sustainable development
Coulomb interaction effects on the electronic structure of radial polarized excitons in nanorings
The electronic structure of radially polarized excitons in structured
nanorings is analyzed, with emphasis in the ground-state properties and their
dependence under applied magnetic fields perpendicular to the ring plane. The
electron-hole Coulomb attraction has been treated rigorously, through numerical
diagonalization of the full exciton Hamiltonian in the non-interacting
electron-hole pairs basis. Depending on the relative weight of the kinetic
energy and Coulomb contributions, the ground-state of polarized excitons has
"extended" or "localized" features. In the first case, corresponding to small
rings dominated by the kinetic energy, the ground-state shows Aharonov-Bohm
(AB) oscillations due to the individual orbits of the building particles of the
exciton. In the localized regime, corresponding to large rings dominated by the
Coulomb interaction, the only remaining AB oscillations are due to the magnetic
flux trapped between the electron and hole orbits. This dependence of the
exciton, a neutral excitation, on the flux difference confirms this feature as
a signature of Coulomb dominated polarized excitons. Analytical approximations
are provided in both regimens, which accurate reproduce the numerical results.Comment: 9 pages, including 6 figure
Tuning hole mobility in InP nanowires
Transport properties of holes in InP nanowires were calculated considering
electron-phonon interaction via deformation potentials, the effect of
temperature and strain fields. Using molecular dynamics, we simulate nanowire
structures, LO-phonon energy renormalization and lifetime. The valence band
ground state changes between light- and heavy-hole character, as the strain
fields and the nanowire size are changed. Drastic changes in the mobility arise
with the onset of resonance between the LO-phonons and the separation between
valence subbands.Comment: 4 pages, 4 figure
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