224,841 research outputs found
Magnetization in two-dimensional electron gas in a perpendicular magnetic field: the roles of edge states and spin-orbit coupling
We study the de Haas--van Alphen (dHvA) oscillations in the magnetization of
a two-dimensional electron gas (2DEG) under the influence of the edge states
and/or the Rashba spin-orbit interaction (SOI). The boundaries of the systems
lift partially the degeneracies of Landau levels (LL's) and the resulting edge
states lead to the changes of both the center and the amplitude of the
sawtoothlike magnetization oscillation. The SOI mixes the spin-up and spin-down
states of neighboring LL's into two unequally spaced energy branches. The
inclusion of SOI changes the well-defined sawtooth pattern of the dHvA
oscillations in the magnetization. The weaker the magnetic field is, the larger
is the change of the dHvA oscillations due to the edge effect and/or the
spin-orbit coupling. Some theoretical results are compared with the
experimental data.Comment: 9 pages, 9 figure
Anticipating Information Needs Based on Check-in Activity
In this work we address the development of a smart personal assistant that is
capable of anticipating a user's information needs based on a novel type of
context: the person's activity inferred from her check-in records on a
location-based social network. Our main contribution is a method that
translates a check-in activity into an information need, which is in turn
addressed with an appropriate information card. This task is challenging
because of the large number of possible activities and related information
needs, which need to be addressed in a mobile dashboard that is limited in
size. Our approach considers each possible activity that might follow after the
last (and already finished) activity, and selects the top information cards
such that they maximize the likelihood of satisfying the user's information
needs for all possible future scenarios. The proposed models also incorporate
knowledge about the temporal dynamics of information needs. Using a combination
of historical check-in data and manual assessments collected via crowdsourcing,
we show experimentally the effectiveness of our approach.Comment: Proceedings of the 10th ACM International Conference on Web Search
and Data Mining (WSDM '17), 201
Giant circular dichroism of a molecule in a region of strong plasmon resonances between two neighboring gold nanocrystals
We report on giant circular dichroism (CD) of a molecule inserted into a
plasmonic hot spot. Naturally occurring molecules and biomolecules have
typically CD signals in the UV range, whereas plasmonic nanocrystals exhibit
strong plasmon resonances in the visible spectral interval. Therefore,
excitations of chiral molecules and plasmon resonances are typically
off-resonant. Nevertheless, we demonstrate theoretically that it is possible to
create strongly-enhanced molecular CD utilizing the plasmons. This task is
doubly challenging since it requires both creation and enhancement of the
molecular CD in the visible region. We demonstrate this effect within the model
which incorporates a chiral molecule and a plasmonic dimer. The associated
mechanism of plasmonic CD comes from the Coulomb interaction which is greatly
amplified in a plasmonic hot spot.Comment: Manuscript: 4+pages, 4 figures; Supplemental_Material: 10 pages, 7
figure
A General Information Theoretical Proof for the Second Law of Thermodynamics
We show that the conservation and the non-additivity of the information,
together with the additivity of the entropy make the entropy increase in an
isolated system. The collapse of the entangled quantum state offers an example
of the information non-additivity. Nevertheless, the later is also true in
other fields, in which the interaction information is important. Examples are
classical statistical mechanics, social statistics and financial processes. The
second law of thermodynamics is thus proven in its most general form. It is
exactly true, not only in quantum and classical physics but also in other
processes, in which the information is conservative and non-additive.Comment: 4 page
scalar glueball in finite-width Gaussian sum rules
Based on a semiclassical expansion for quantum chromodynamics in the
instanton liquid background, the correlation function of the scalar
glueball current is given, and the properties of the scalar glueball
are studied in the framework of Gaussian sum rules. Besides the pure classical
and quantum contributions, the contributions arising from the interactions
between the classical instanton fields and quantum gluons are come into play.
Instead of the usual zero-width approximation for the resonance, the
Breit-Wigner form for the spectral function of the finite-width resonance is
adopted. The family of the Gaussian sum rules for the scalar glueball in
quantum chromodynamics with and without light quarks is studied. A consistency
between the subtracted and unsubtracted sum rules is very well justified, and
the values of the decay width and the coupling to the corresponding current for
the resonance, in which the scalar glueball fraction is dominant, are
obtained.Comment: 18pages, 9figure
Microcanonical Thermodynamics of First Order Phase Transitions studied in the Potts Model
Phase transitions of first and second order can easily be distinguished in
small systems in the microcanonical ensemble. Configurations of phase
coexistence, which are suppressed in the canonical formulation, carry important
information about the main characteristics of first order phase transitions
like the transition temperature, the latent heat, and the interphase surface
tension. The characterisitc backbending of the micro- canonical caloric
equation of state T(E) (not to be confused with the well known Van der Waals
loops in ordinary thermodynamics) leading to a negative specific heat is
intimatly linked to the interphase surface entropy.Comment: Latex, 4 eps-figures, graphicx.st
Topological thermoelectric effects in spin-orbit coupled electron and hole doped semiconductors
We compute the intrinsic contributions to the Berry-phase mediated anomalous
Hall and Nernst effects in electron- and hole-doped semiconductors in the
presence of an in-plane magnetic field as well as Rashba and Dresselhaus spin
orbit couplings. For both systems we find that the regime of chemical potential
which supports the topological superconducting state in the presence of
superconducting proximity effect can be characterized by plateaus in the
topological Hall and Nernst coefficients flanked by well-defined peaks marking
the emergence of the topological regime. The plateaus arise from a clear
momentum space separation between the region where the Berry curvature is
peaked (at the `near-band-degeneracy' points) and the region where the single
(or odd number of) Fermi surface lies in the Brillouin zone. The plateau for
the Nernst coefficient is at vanishing magnitudes surrounded by two peaks of
opposite signs as a function of the chemical potential. These results could be
useful for experimentally deducing the chemical potential regime suitable for
realizing topological states in the presence of proximity effect.Comment: 8 pages, 8 figure
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