2,863 research outputs found
Chemical potential shift in La(1-x)Sr(x)MnO(3): Photoemission test of the phase separation scenario
We have studied the chemical potential shift in La(1-x)Sr(x)MnO(3) as a
function of doped hole concentration by core-level x-ray photoemission. The
shift is monotonous, which means that there is no electronic phase separation
on a macroscopic scale, whereas it is consistent with the nano-meter scale
cluster formation induced by chemical disorder. Comparison of the observed
shift with the shift deduced from the electronic specific heat indicates that
hole doping in La(1-x)Sr(x)MnO(3) is well described by the rigid-band picture.
In particular no mass enhancement toward the metal-insulator boundary was
implied by the chemical potential shift, consistent with the electronic
specific heat data.Comment: 7 pages, 3 figures, to be published in Europhysics Letter
A direct method of solution for the Fokas-Lenells derivative nonlinear Schr\"odinger equation: I. Bright soliton solutions
We develop a direct method of solution for finding the bright -soliton
solution of the Fokas-Lenells derivative nonlinear Schr\"odinger equation. The
construction of the solution is performed by means of a purely algebraic
procedure using an elementary theory of determinants and does not rely on the
inverse scattering transform method. We present two different expressions of
the solution both of which are expressed as a ratio of determinants. We then
investigate the properties of the solutions and find several new features.
Specifically, we derive the formula for the phase shift caused by the
collisions of bright solitons.Comment: To appear in J. Phys. A: Math. Theor. 45(2012) Ma
Use of untreated wastewater in peri-urban agriculture in Pakistan: risks and opportunities
Water reuse / Waste waters / Water quality / Groundwater / Irrigation practices / Soil properties / Environmental effects / Conjunctive use / Pakistan / Haroonabad
Charge ordering in the spinels AlVO and LiVO
We develop a microscopic theory for the charge ordering (CO) transitions in
the spinels AlVO and LiVO (under pressure). The high degeneracy
of CO states is lifted by a coupling to the rhombohedral lattice deformations
which favors transition to a CO state with inequivalent V(1) and V(2) sites
forming Kagom\'e and trigonal planes respectively. We construct an extended
Hubbard type model including a deformation potential which is treated in
unrestricted Hartree Fock approximation and describes correctly the observed
first-order CO transition. We also discuss the influence of associated orbital
order. Furthermore we suggest that due to different band fillings AlVO
should remain metallic while LiVO under pressure should become a
semiconductor when charge disproportionation sets in
Parametric Representation for the Multisoliton Solution of the Camassa-Holm Equation
The parametric representation is given to the multisoliton solution of the
Camassa-Holm equation. It has a simple structure expressed in terms of
determinants. The proof of the solution is carried out by an elementary theory
of determinanats. The large time asymptotic of the solution is derived with the
fomula for the phase shift. The latter reveals a new feature when compared with
the one for the typical soliton solutions. The peakon limit of the phase shift
ia also considered, showing that it reproduces the known result.Comment: 14 page
Quantum Shock Waves - the case for non-linear effects in dynamics of electronic liquids
Using the Calogero model as an example, we show that the transport in
interacting non-dissipative electronic systems is essentially non-linear.
Non-linear effects are due to the curvature of the electronic spectrum near the
Fermi energy. As is typical for non-linear systems, propagating wave packets
are unstable. At finite time shock wave singularities develop, the wave packet
collapses, and oscillatory features arise. They evolve into regularly
structured localized pulses carrying a fractionally quantized charge - {\it
soliton trains}. We briefly discuss perspectives of observation of Quantum
Shock Waves in edge states of Fractional Quantum Hall Effect and a direct
measurement of the fractional charge
Modulation theory of quantum tunneling into a Calogero-Sutherland fluid
Quantum hydrodynamics of interacting electrons with a parabolic single
particle spectrum is studied using the Calogero-Sutherland model. The effective
action and modulation equations, describing evolution of periodic excitations
in the fluid, are derived. Applications to the problem of a single electron
tunneling into the FQHE edge state are discussed
Frustrated minority spins in GeNi2O4
Recently, two consecutive phase transitions were observed, upon cooling, in
an antiferromagnetic spinel GeNiO at K and
K, respectively \cite{matsuno, crawford}. Using unpolarized and polarized
elastic neutron scattering we show that the two transitions are due to the
existence of frustrated minority spins in this compound. Upon cooling, at
the spins on the \kagome planes order ferromagnetically in the
plane and antiferromagnetically between the planes (phase I), leaving the spins
on the triangular planes that separate the \kagome planes frustrated
and disordered. At the lower , the triangular spins also order in the
plane (phase II). We also present a scenario involving exchange
interactions that qualitatively explains the origin of the two purely magnetic
phase transitions
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