8,919 research outputs found
Tuning Hole Mobility, Concentration, and Repulsion in High- Cuprates via Apical Atoms
Using a newly developed first-principles Wannier-states approach that takes
into account large on-site Coulomb repulsion, we derive the effective
low-energy interacting Hamiltonians for several prototypical high-
superconducting cuprates. The material dependence is found to originate
primarily from the different energy of the apical atom state.
Specifically, the general properties of the low-energy hole state, namely the
Zhang-Rice singlet, are significantly modified by a triplet state associated
with this state, via additional intra-sublattice hoppings,
nearest-neighbor "super-repulsion", and other microscopic many-body processes.
Possible implications on modulation of , local superconducting gaps,
charge distribution, hole mobility, electron-phonon interaction, and
multi-layer effects are discussed.Comment: 5 pages, 3 figures, 1 tabl
Rapid algorithm for identifying backbones in the two-dimensional percolation model
We present a rapid algorithm for identifying the current-carrying backbone in
the percolation model. It applies to general two-dimensional graphs with open
boundary conditions. Complemented by the modified Hoshen-Kopelman cluster
labeling algorithm, our algorithm identifies dangling parts using their local
properties. For planar graphs, it finds the backbone almost four times as fast
as Tarjan's depth-first-search algorithm, and uses the memory of the same size
as the modified Hoshen-Kopelman algorithm. Comparison with other algorithms for
backbone identification is addressed.Comment: 5 pages with 5 eps figures. RevTeX 3.1. Clarify the origin of the
hull-generating algorith
Joint Domain Based Massive Access for Small Packets Traffic of Uplink Wireless Channel
The fifth generation (5G) communication scenarios such as the cellular
network and the emerging machine type communications will produce massive small
packets. To support massive connectivity and avoid signaling overhead caused by
the transmission of those small packets, this paper proposes a novel method to
improve the transmission efficiency for massive connections of wireless uplink
channel. The proposed method combines compressive sensing (CS) with power
domain NOMA jointly, especially neither the scheduling nor the centralized
power allocation is necessary in the method. Both the analysis and simulation
show that the method can support up to two or three times overloading.Comment: 6 pages, 5 figures.submitted to globecom 201
Unified Picture for Magnetic Correlations in Iron-Based Superconductors
The varying metallic antiferromagnetic correlations observed in iron-based
superconductors are unified in a model consisting of both itinerant electrons
and localized spins. The decisive factor is found to be the sensitive
competition between the superexchange antiferromagnetism and the
orbital-degenerate double-exchange ferromagnetism. Our results reveal the
crucial role of Hund's rule coupling for the strongly correlated nature of the
system and suggest that the iron-based superconductors are closer kin to
manganites than cuprates in terms of their diverse magnetism and incoherent
normal-state electron transport. This unified picture would be instrumental for
exploring other exotic properties and the mechanism of superconductivity in
this new class of superconductors.Comment: Revised for publication. 3 figure
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