846 research outputs found
Spin nematics and magnetization plateau transition in anisotropic Kagome magnets
We study S=1 kagome antiferromagnets with isotropic Heisenberg exchange
and strong easy axis single-ion anisotropy . For , the low-energy
physics can be described by an effective model with
antiferromagnetic and ferromagnetic .
Exploiting this connection, we argue that non-trivial ordering into a
"spin-nematic" occurs whenever dominates over , and discuss its
experimental signatures. We also study a magnetic field induced transition to a
magnetization plateau state at magnetization 1/3 which breaks lattice
translation symmetry due to ordering of the and occupies a lobe in the
- phase diagram.Comment: 4pages, two-column format, three .eps figure
Analyzing Urban Expansion and Spatial Growth Patterns in Barahathawa Municipality of Central Tarai Region, Nepal
The rapid transformation of rural settlements into municipalities in Nepal has brought significant changes in land use, and urban expansion and growth patterns mostly through the conversion of agricultural land into the built-up area. The issue is studied taking a case of the rapidly growing town, Barahathawa Municipality of Tarai Region of Sarlahi District. After the declaration of the municipality, several new roads have been opened and upgraded; and the municipality is well-connected to the national transportation network. After promulgated the Constitution of Nepal 2015 and functioning the elected local body, the municipality budget has been increased significantly as a result of increasing municipal investment in socio-economic and physical infrastructure development and environmental protection which has attracted people, goods, and services creating the zone of influence on the municipality. One of the changes found in the municipality is the increasing built-up area and expansion of urban growth through the decreasing agricultural land. Urban growth has been observed taking place around the Barahathawa Bazaar and main roadsides. The built-up area in Barahathawa municipality has remarkably increased by 183percent with the decrease of shrub and agricultural land within 10 years. Implications of such spatial and temporal dynamics have been a core issue of urban planning in most of the newly declared municipalities in Nepal
Parabolic resonances and instabilities in near-integrable two degrees of freedom Hamiltonian flows
When an integrable two-degrees-of-freedom Hamiltonian system possessing a
circle of parabolic fixed points is perturbed, a parabolic resonance occurs. It
is proved that its occurrence is generic for one parameter families
(co-dimension one phenomenon) of near-integrable, t.d.o. systems. Numerical
experiments indicate that the motion near a parabolic resonance exhibits new
type of chaotic behavior which includes instabilities in some directions and
long trapping times in others. Moreover, in a degenerate case, near a {\it flat
parabolic resonance}, large scale instabilities appear. A model arising from an
atmospherical study is shown to exhibit flat parabolic resonance. This supplies
a simple mechanism for the transport of particles with {\it small} (i.e.
atmospherically relevant) initial velocities from the vicinity of the equator
to high latitudes. A modification of the model which allows the development of
atmospherical jets unfolds the degeneracy, yet traces of the flat instabilities
are clearly observed
Band-center metal-insulator transition in bond-disordered graphene
We study the transport properties of a tight-binding model of non-interacting
fermions with random hopping on the honeycomb lattice. At the particle-hole
symmetric chemical potential, the absence of diagonal disorder (random onsite
potentials) places the system in the well-studied chiral orthogonal
universality class of disordered fermion problems, which are known to exhibit
both a critical metallic phase and a dimerization-induced localized phase.
Here, our focus is the behavior of the two-terminal conductance and the
Lyapunov spectrum in quasi-1D geometry near the dimerization-driven transition
from the metallic to the localized phase. For a staggered dimerization pattern
on the square and honeycomb lattices, we find that the renormalized
localization length ( denotes the width of the sample) and the
typical conductance display scaling behavior controlled by a crossover
length-scale that diverges with exponent as the critical
point is approached. However, for the plaquette dimerization pattern, we
observe a relatively large exponent revealing an apparent
non-universality of the delocalization-localization transition in the BDI
symmetry class.Comment: 7+2 pages, 6 figure
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