114,061 research outputs found
A compiled catalog of rotation measures of radio point sources
We compiled a catalog of Faraday rotation measures (RMs) for 4553
extragalactic radio point sources ublished in literature. These RMs were
derived from multi-frequency polarization observations. The RM data are
compared to those in the NRAO VLA Sky Survey (NVSS) RM catalog. We reveal a
systematic uncertainty of about \,rad~m in the NVSS RM
catalog. The Galactic foreground RM is calculated through a weighted averaging
method by using the compiled RM catalog together with the NVSS RM catalog, with
careful consideration of uncertainties in the RM data. The data from the
catalog and the interface for the Galactic foreground RM calculations are
publicly available on the webpage: http://zmtt.bao.ac.cn/RM/.Comment: 17 pages, 8 figures. Published already, at
http://www.raa-journal.org/raa/index.php/raa/article/view/171
Nonequilibrium electron transport in strongly correlated molecular junctions
We investigate models of molecular junctions which constitute minimal
Hamiltonians to account for zero-bias-anomaly and the satellite features of
inelastic transport by molecular phonons. Through nonlinear transport
calculations with the imaginary-time nonequilibrium formalism, a HOMO-LUMO
model with Anderson-Holstein interaction is shown to produce co-tunneling
conductance peak in the vicinity of Kondo resonance which is mediated by a
re-emergent many-body resonance assisted by phonon excitations at bias equal to
the phonon frequency. Destruction of the resonance leads to
negative-differential-resistance in the sequential tunneling regime
Chemical control of orbital polarization in artificially structured transition-metal oxides: La2NiXO6 (X=B, Al, Ga, In) from first principles
The application of modern layer-by-layer growth techniques to
transition-metal oxide materials raises the possibility of creating new classes
of materials with rationally designed correlated electron properties. An
important step toward this goal is the demonstration that electronic structure
can be controlled by atomic composition. In compounds with partially occupied
transition-metal d shells, one important aspect of the electronic structure is
the relative occupancy of different d orbitals. Previous work has established
that strain and quantum confinement can be used to influence orbital occupancy.
In this paper we demonstrate a different modality for orbital control in
transition-metal oxide heterostructures, using density-functional band
calculations supplemented by a tight-binding analysis to show that the choice
of nontransition-metal counterion X in transition-metal oxide heterostructures
composed of alternating LaNiO3 and LaXO3 units strongly affects orbital
occupancy, changing the magnitude and in some cases the sign of the orbital
polarization
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