4,680 research outputs found
Phase diagram of Kondo-Heisenberg model on honeycomb lattice with geometrical frustration
We calculated the phase diagram of the Kondo-Heisenberg model on
two-dimensional honeycomb lattice with both nearest-neighbor and
next-nearest-neighbor antiferromagnetic spin exchanges, to investigate the
interplay between RKKY and Kondo interactions at presence of magnetic
frustration. Within a mean-field decoupling technology in slave-fermion
representation, we derived the zero-temperature phase diagram as a function of
Kondo coupling and frustration strength . The geometrical frustration
can destroy the magnetic order, driving the original antiferromagnetic (AF)
phase to non-magnetic valence bond state (VBS). In addition, we found two
distinct VBS. As is increased, a phase transition from AF to Kondo
paramagnetic (KP) phase occurs, without the intermediate phase coexisting AF
order with Kondo screening found in square lattice systems. In the KP phase,
the enhancement of frustration weakens the Kondo screening effect, resulting in
a phase transition from KP to VBS. We also found a process to recover the AF
order from VBS by increasing in a wide range of frustration strength. Our
work may provide deeper understanding for the phase transitions in
heavy-fermion materials, particularly for those exhibiting triangular
frustration
Reexploration of interacting holographic dark energy model: Cases of interaction term excluding the Hubble parameter
In this paper, we make a deep analysis for the five typical interacting
holographic dark energy models with the interaction terms , , , , and , respectively.
We obtain observational constraints on these models by using the type Ia
supernova data (the Joint Light-curve Analysis sample), the cosmic microwave
background data (Planck 2015 distance priors), the baryon acoustic oscillations
data, and the direct measurement of the Hubble constant. We find that the
values of for all the five models are almost equal
(around~699), indicating that the current observational data equally favor
these IHDE models. In addition, a comparison with the cases of interaction term
involving the Hubble parameter is also made.Comment: 14 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1710.0306
New feature of low charm quark hadronization in collisions at TeV
Treating the light-flavor constituent quarks and antiquarks that can well
describe the data of light-flavor hadrons in collisions at
TeV as the underlying source of chromatically neutralizing the charm quarks of
low transverse momenta (), we show that the experimental data of
spectra of single-charm hadrons , ,
and at mid-rapidity in the low range
( GeV/) in collisions at TeV can
be well understood by the equal-velocity combination of perturbatively-created
charm quarks and those light-flavor constituent quarks and antiquarks. This
suggests a possible new scenario of low charm quark hadronization, in
contrast to the traditional fragmentation mechanism, in collisions at LHC
energies. This is also another support for the exhibition of the effective
constituent quark degrees of freedom for the small parton system created in
collisions at LHC energies.Comment: 7 pages, 5 figure
The edge engineering of topological Bi(111) bilayer
A topological insulator is a novel quantum state, characterized by
symmetry-protected non-trivial edge/surface states. Our first-principle
simulations show the significant effects of the chemical decoration on edge
states of topological Bi(111) bilayer nanoribbon, which remove the trivial edge
state and recover the Dirac linear dispersion of topological edge state. By
comparing the edge states with and without chemical decoration, the Bi(111)
bilayer nanoribbon offers a simple system for assessing conductance fluctuation
of edge states. The chemical decoration can also modify the penetration depth
and the spin texture of edge states. A low-energy effective model is proposed
to explain the distinctive spin texture of Bi(111) bilayer nanoribbon, which
breaks the spin-momentum orthogonality along the armchair edge.Comment: 5 pages, 5 figure
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