16,033 research outputs found
SET based experiments for HTSC materials: II
The cuprates seem to exhibit statistics, dimensionality and phase transitions
in novel ways. The nature of excitations
[i.e. quasiparticle or collective], spin-charge separation, stripes [static
and dynamics], inhomogeneities, psuedogap, effect of impurity dopings [e.g. Zn,
Ni] and any other phenomenon in these materials must be consistently
understood. In this note we further discuss our original suggestion of using
Single Electron Tunneling Transistor
[SET] based experiments to understand the role of charge dynamics in these
systems. Assuming that SET operates as an efficient charge detection system we
can expect to understand the underlying physics of charge transport and charge
fluctuations in these materials for a range of doping. Experiments such as
these can be classed in a general sense as mesoscopic and nano characterization
of cuprates and related materials. In principle such experiments can show if
electron is fractionalized in cuprates as indicated by ARPES data. In contrast
to flux trapping experiments SET based experiments are more direct in providing
evidence about spin-charge separation. In addition a detailed picture of nano
charge dynamics in cuprates may be obtained.Comment: 10 pages revtex plus four figures; ICMAT 2001 Conference Symposium P:
P10-0
Anomalous random correlations of force constants on the lattice dynamical properties of disordered Au-Fe alloys
Au-Fe alloys are of immense interest due to their biocompatibility, anomalous
hall conductivity, and applications in various medical treatment. However,
irrespective of the method of preparation, they often exhibit a high-level of
disorder, with properties sensitive to the thermal or magnetic annealing
temperatures. We calculate lattice dynamical properties of AuFe
alloys using density functional theory methods, where, being a multisite
property, reliable interatomic force constant (IFC) calculations in disordered
alloys remain a challenge. We follow a two fold approach: (1) an accurate IFC
calculation in an environment with nominally zero chemical pair correlations to
mimic the homogeneously disordered alloy; and (2) a configurational averaging
for the desired phonon properties (e.g., dispersion, density of states, and
entropy). We find an anomalous change in the IFC's and phonon dispersion (split
bands) near =0.19, which is attributed to the local stiffening of the Au-Au
bonds when Au is in the vicinity of Fe. Other results based on mechanical and
thermo-physical properties reflect a similar anomaly: Phonon entropy, e.g.,
becomes negative below =0.19, suggesting a tendency for chemical unmixing,
reflecting the onset of miscibility gap in the phase diagram. Our results match
fairly well with reported data, wherever available
Dead cone due to parton virtuality
A general expression for the dead cone of gluons radiated by virtual partons
has been derived. The conventional dead cone for massive on-shell quarks and
the dead cone for the massless virtual partons have been obtained by using
different limits of the general expression. Radiative suppression due to the
virtuality of initial parton jets in Heavy-Ion Collisions (HIC) has been
discussed. It is observed that the suppression caused by the high virtuality is
overwhelmingly large as compared to that on account of conventional dead-cone
of heavy quarks. The dead cone due to virtuality may play a crucial role in
explaining the observed similar suppression patterns of light and heavy quarks
jets in heavy ion collisions at Relativistic Heavy Ion Collider (RHIC)
In re Harrods Ltd.: The Brussels Convention and the Proper Application of Forum Non Conveniens to Non-Contracting States
Although the doctrine of forum non conveniens is unknown in Continental legal systems, Community law does not prevent English courts from preserving their discretion to stay proceedings, in conflicts involving a defendant domiciliary, in favor of more appropriate courts in a non-Contracting State. Where the provisions of the Brussels Convention do not address a legal question, the answer must be sought in the objectives and scheme of the Convention. The English Court of Appeals in Harrods properly understood that Community law does not require ritualistic reliance on the Convention\u27s jurisdiction conferring provisions in cases involving a defendant domiciled in a Contracting State and the jurisdiction of a court in a non-Contracting State
On entropy, specific heat, susceptibility and Rushbrooke inequality in percolation
We investigate percolation, a probabilistic model for continuous phase
transition (CPT), on square and weighted planar stochastic lattices. In its
thermal counterpart, entropy is minimally low where order parameter (OP) is
maximally high and vice versa. Besides, specific heat, OP and susceptibility
exhibit power-law when approaching the critical point and the corresponding
critical exponents respectably obey the Rushbrooke
inequality (RI) . Their analogues in percolation,
however, remain elusive. We define entropy, specific heat and redefine
susceptibility for percolation and show that they behave exactly in the same
way as their thermal counterpart. We also show that RI holds for both the
lattices albeit they belong to different universality classes.Comment: 5 pages, 3 captioned figures, to appear as a Rapid Communication in
Physical Review E, 201
Green's function multiple-scattering theory with a truncated basis set: An Augmented-KKR formalism
Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is
an efficient site-centered, electronic-structure technique for addressing an
assembly of scatterers. Wave-functions are expanded in a spherical-wave
basis on each scattering center and indexed up to a maximum orbital and
azimuthal number , while scattering matrices, which
determine spectral properties, are truncated at where phase
shifts are negligible. Historically, is set equal
to ; however, a more proper procedure retains free-electron and
single-site contributions for with set to
zero [Zhang and Butler, Phys. Rev. B {\bf 46}, 7433]. We present a numerically
efficient and accurate \emph{augmented}-KKR Green's function formalism that
solves the KKR secular equations by matrix inversion [ process
with rank ] and includes higher-order contributions via
linear algebra [ process with rank ].
Augmented-KKR yields properly normalized wave-functions, numerically cheaper
basis-set convergence, and a total charge density and electron count that
agrees with Lloyd's formula. For fcc Cu, bcc Fe and L CoPt, we present the
formalism and numerical results for accuracy and for the convergence of the
total energies, Fermi energies, and magnetic moments versus for a
given .Comment: 7 pages, 5 figure
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