17,818 research outputs found
On the Distribution of a Second Class Particle in the Asymmetric Simple Exclusion Process
We give an exact expression for the distribution of the position X(t) of a
single second class particle in the asymmetric simple exclusion process (ASEP)
where initially the second class particle is located at the origin and the
first class particles occupy the sites {1,2,...}
Collective excitations in double-layer quantum Hall systems
We study the collective excitation spectra of double-layer quantum-Hall
systems using the single mode approximation. The double-layer in-phase density
excitations are similar to those of a single-layer system. For out-of-phase
density excitations, however, both inter-Landau-level and intra-Landau-level
double-layer modes have finite dipole oscillator strengths. The oscillator
strengths at long wavelengths for the latter transitions are shifted upward by
interactions by identical amounts proportional to the interlayer Coulomb
coupling. The intra-Landau-level out-of-phase mode has a gap when the ground
state is incompressible except in the presence of spontaneous inter-layer
coherence. We compare our results with predictions based on the
Chern-Simons-Landau-Ginzburg theory for double-layer quantum Hall systems.Comment: RevTeX, 21 page
The Role of Electron-electron Interactions in Graphene ARPES Spectra
We report on a theoretical study of the influence of electron-electron
interactions on ARPES spectra in graphene that is based on the
random-phase-approximation and on graphene's massless Dirac equation continuum
model. We find that level repulsion between quasiparticle and plasmaron
resonances gives rise to a gap-like feature at small k. ARPES spectra are
sensitive to the electron-electron interaction coupling strength and might enable an experimental determination of this material parameter.Comment: 5 Pages, 4 Figures, Submitte
EPR and ferromagnetism in diluted magnetic semiconductor quantum wells
Motivated by recent measurements of electron paramagnetic resonance (EPR)
spectra in modulation-doped CdMnTe quantum wells, [F.J. Teran {\it et al.},
Phys. Rev. Lett. {\bf 91}, 077201 (2003)], we develop a theory of collective
spin excitations in quasi-two-dimensional diluted magnetic semiconductors
(DMSs). Our theory explains the anomalously large Knight shift found in these
experiments as a consequence of collective coupling between Mn-ion local
moments and itinerant-electron spins. We use this theory to discuss the physics
of ferromagnetism in (II,Mn)VI quantum wells, and to speculate on the
temperature at which it is likely to be observed in n-type modulation doped
systems.Comment: 4 pages, 1 figur
Jack polynomials with prescribed symmetry and hole propagator of spin Calogero-Sutherland model
We study the hole propagator of the Calogero-Sutherland model with SU(2)
internal symmetry. We obtain the exact expression for arbitrary non-negative
integer coupling parameter and prove the conjecture proposed by one of
the authors. Our method is based on the theory of the Jack polynomials with a
prescribed symmetry.Comment: 12 pages, REVTEX, 1 eps figur
Energy Relaxation in the Integer Quantum Hall Regime
We investigate the energy exchanges along an electronic quantum channel
realized in the integer quantum Hall regime at filling factor . One of
the two edge channels is driven out-of-equilibrium and the resulting electronic
energy distribution is measured in the outer channel, after several propagation
lengths mm. Whereas there are no discernable energy
transfers toward thermalized states, we find efficient energy redistribution
between the two channels without particle exchanges. At long distances
m, the measured energy distribution is a hot Fermi function whose
temperature is lower than expected for two interacting channels, which suggests
the contribution of extra degrees of freedom. The observed short energy
relaxation length challenges the usual description of quantum Hall excitations
as quasiparticles localized in one edge channel.Comment: To be published in PRL, 10 pages including supplementary materia
An interacting spin flip model for one-dimensional proton conduction
A discrete asymmetric exclusion process (ASEP) is developed to model proton
conduction along one-dimensional water wires. Each lattice site represents a
water molecule that can be in only one of three states; protonated,
left-pointing, and right-pointing. Only a right(left)-pointing water can accept
a proton from its left(right). Results of asymptotic mean field analysis and
Monte-Carlo simulations for the three-species, open boundary exclusion model
are presented and compared. The mean field results for the steady-state proton
current suggest a number of regimes analogous to the low and maximal current
phases found in the single species ASEP [B. Derrida, Physics Reports, {\bf
301}, 65-83, (1998)]. We find that the mean field results are accurate
(compared with lattice Monte-Carlo simulations) only in the certain regimes.
Refinements and extensions including more elaborate forces and pore defects are
also discussed.Comment: 13pp, 6 fig
Magnetic Anisotropy in Quantum Hall Ferromagnets
We show that the sign of magnetic anisotropy energy in quantum Hall
ferromagnets is determined by a competition between electrostatic and exchange
energies. Easy-axis ferromagnets tend to occur when Landau levels whose states
have similar spatial profiles cross. We report measurements of integer QHE
evolution with magnetic-field tilt. Reentrant behavior observed for the QHE at high tilt angles is attributed to easy-axis anisotropy. This
interpretation is supported by a detailed calculation of the magnetic
anisotropy energy.Comment: 12 pages, 3 figures, submitted to Phys. Rev. Let
- …