40,010 research outputs found
Theoretical spin-wave dispersions in the antiferromagnetic phase AF1 of MnWO based on the polar atomistic model in P2
The spin wave dispersions of the low temperature antiferromagnetic phase
(AF1) MnWO have been numerically calculated based on the recently reported
non-collinear spin configuration with two different canting angles. A
Heisenberg model with competing magnetic exchange couplings and single-ion
anisotropy terms could properly describe the spin wave excitations, including
the newly observed low-lying energy excitation mode =0.45 meV
appearing at the magnetic zone centre. The spin wave dispersion and intensities
are highly sensitive to two differently aligned spin-canting sublattices in the
AF1 model. Thus this study reinsures the otherwise hardly provable hidden polar
character in MnWO.Comment: 7 pages, 5 figure
Crystal structure, incommensurate magnetic order and ferroelectricity in mncuwo (x=0-0.19)
We have carried out a systematic study on the effect of Cu doping on nuclear,
magnetic, and dielectric properties in MnCuWO for
by a synergic use of different techniques, viz, heat
capacity, magnetization, dielectric, and neutron powder diffraction
measurements. Via heat capacity and magnetization measurements we show that
with increasing Cu concentration magnetic frustration decreases, which leads to
the stabilization of commensurate magnetic ordering. This was further verified
by temperature-dependent unit cell volume changes derived from neutron
diffraction measurements which was modeled by the Gr\"{u}neisen approximation.
Dielectric measurements show a low temperature phase transition below about
9-10 K. Further more, magnetic refinements reveal no changes below this
transition indicating a possible spin-flop transition which is unique to the Cu
doped system. From these combined studies we have constructed a magnetoelectric
phase diagram of this compound.Comment: 9 pages, 9 figures, accepted for publication in PR
Possible spin triplet superconductivity in NaCoOH0
Combining symmetry based considerations with inputs from available
experimental results, we make the case that a novel spin-triplet
superconductivity triggered by antiferromagnetic fluctuations may be realized
in the newly discovered layered cobaltide NaCoOHO. In the
proposed picture, unaccessable via resonating-valence-bond physics extrapolated
from half-filling, the pairing process is similar to that advanced for
SrRuO, but enjoys a further advantage coming from the hexagonal
structure of the Fermi-surface which gives a stronger pairing tendency.Comment: 4 page
Signatures of Non-commutative QED at Photon Colliders
In this paper we study non-commutative (NC) QED signatures at photon
colliders through pair production of charged leptons and
charged scalars . The NC corrections for the fermion pair production
can be easily obtained since NC QED with fermions has been extensively studied
in the literature. NC QED with scalars is less studied. To obtain the cross
section for productions, we first investigate the structure of NC QED
with scalars, and then study the corrections due to the NC geometry to the
ordinary QED cross sections. Finally by folding in the photon spectra for a
collider with laser back-scattered photons from the
machine, we obtain 95% CL lower bound on the NC scale using the above two
processes. We find that, with , and TeV and
integrated luminosity , the NC scale up to 0.7, 1.2, and 1.6
TeV can be probed, respectively, while, for monochromatic photon beams, these
numbers become 1.1, 1.7, 2.6 TeV, respectively.Comment: 16 pages, 7 figure
Opinion diversity and community formation in adaptive networks
It is interesting and of significant importance to investigate how network
structures co-evolve with opinions. The existing models of such co-evolution
typically lead to the final states where network nodes either reach a global
consensus or break into separated communities, each of which holding its own
community consensus. Such results, however, can hardly explain the richness of
real-life observations that opinions are always diversified with no global or
even community consensus, and people seldom, if not never, totally cut off
themselves from dissenters. In this article, we show that, a simple model
integrating consensus formation, link rewiring and opinion change allows
complex system dynamics to emerge, driving the system into a dynamic
equilibrium with co-existence of diversified opinions. Specifically, similar
opinion holders may form into communities yet with no strict community
consensus; and rather than being separated into disconnected communities,
different communities remain to be interconnected by non-trivial proportion of
inter-community links. More importantly, we show that the complex dynamics may
lead to different numbers of communities at steady state with a given tolerance
between different opinion holders. We construct a framework for theoretically
analyzing the co-evolution process. Theoretical analysis and extensive
simulation results reveal some useful insights into the complex co-evolution
process, including the formation of dynamic equilibrium, the phase transition
between different steady states with different numbers of communities, and the
dynamics between opinion distribution and network modularity, etc.Comment: 12 pages, 8 figures, Journa
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