22,281 research outputs found
Defects in Heavy-Fermion Materials: Unveiling Strong Correlations in Real Space
Complexity in materials often arises from competing interactions at the
atomic length scale. One such example are the strongly correlated heavy-fermion
materials where the competition between Kondo screening and antiferromagnetic
ordering is believed to be the origin of their puzzling non-Fermi-liquid
properties. Insight into such complex physical behavior in strongly correlated
electron systems can be gained by impurity doping. Here, we develop a
microscopic theoretical framework to demonstrate that defects implanted in
heavy-fermion materials provide an opportunity for unveiling competing
interactions and their correlations in real space. Defect-induced perturbations
in the electronic and magnetic correlations possess characteristically
different spatial patterns that can be visualized via their spectroscopic
signatures in the local density of states or non-local spin susceptibility.
These real space patterns provide insight into the complex electronic structure
of heavy-fermion materials, the light or heavy character of the perturbed
states, and the hybridization between them. The strongly correlated nature of
these materials also manifests itself in highly non-linear quantum interference
effects between defects that can drive the system through a first-order phase
transition to a novel inhomogeneous ground state.Comment: 11 pages, 7 figure
Two-fluid behavior of the Kondo lattice in the 1/N slave boson approach
It has been recently shown by Nakatsuji, Pines, and Fisk [S. Nakatsuji, D.
Pines, and Z. Fisk, Phys. Rev. Lett. 92, 016401 (2004)] from the
phenomenological analysis of experiments in Ce1-xLaxCoIn5 and CeIrIn5 that
thermodynamic and transport properties of Kondo lattices below coherence
temperature can be very successfully described in terms of a two-fluid model,
with Kondo impurity and heavy electron Fermi liquid contributions. We analyze
thermodynamic properties of Kondo lattices using 1/N slave boson treatment of
the periodic Anderson model and show that these two contributions indeed arise
below the coherence temperature. We find that the Kondo impurity contribution
to thermodynamics corresponds to thermal excitations into the flat portion of
the energy spectrum.Comment: 7 pages, 2 figure
Spacetime Dependent Lagrangians and Weak-Strong Duality : Sine Gordon and Massive Thirring Models
The formalism of spacetime dependent lagrangians developed in Ref.1 is
applied to the Sine Gordon and massive Thirring models.It is shown that the
well-known equivalence of these models (in the context of weak-strong duality)
can be understood in this approach from the same considerations as described in
[1] for electromagnetic duality. A further new result is that all these can be
naturally linked to the fact that the holographic principle has analogues at
length scales much larger than quantum gravity. There is also the possibility
of {\it noncommuting coodinates} residing on the boundaries. PACS: 11.15.-q:
11.10/EfComment: Latex, 16 pages, article shortened, references added, minor typos
correcte
Hidden Order Transition in URu2Si2 and the Emergence of a Coherent Kondo Lattice
Using a large-N approach, we demonstrate that the differential conductance
and quasi-particle interference pattern measured in recent scanning tunneling
spectroscopy experiments (A.R. Schmidt et al. Nature 465, 570 (2010); P.
Aynajian et al., PNAS 107, 10383 (2010)) in URu2Si2 are consistent with the
emergence of a coherent Kondo lattice below its hidden order transition (HOT).
Its formation is driven by a significant increase in the quasi-particle
lifetime, which could arise from the emergence of a yet unknown order parameter
at the HOT.Comment: 5 pages, 3 figure
RothC - A model for the turnover of carbon in soil Model description and users guide (Windows version) (updated June 2014)
An Evaluation of Performance and Structural Change in Employment- U.S., Nebraska, and Omaha Area Economies, 1988 to 1995
A periodic comparative evaluation of employment and its composition is worthwhile since employment is one of the most basic determinants of the health of the economy and quality of life. Changes in employment over time reflect restructuring of an economy and, ultimately, have social impacts. Moreover, the underlying trends of employment give an indication of an economy\u27s future growth and wellbeing. A future article will evaluate personal income as a measure of economic performance.
This article examines employment data developed by the U. S. Department of Commerce, Bureau of Economic Analysis (BEA) and compiled by the Bureau of Business Research (BBR). To provide a consistent and comparable analysis, the initial and terminal years of the study, 1988 and 1995, both represent periods of healthy economic growth. The data tables summarize the economies of the U. S. (Table I), Nebraska (Table 2) and the Omaha Area (Tables 3 and 4). The Omaha area includes the Nebraska counties of Douglas, Sarpy, and Washington in Table 3. Pottawattamie County, Iowa is added to the Omaha area in Table 4. Pottawattamie County is also presented separately in Table 5 to show its growth relative to the rest of the Omaha Area.
Employment Changes
Summary of Employment Changes in the Economies
Conclusio
Vacuum decay and internal symmetries
We study the effects of internal symmetries on the decay by bubble nucleation
of a metastable false vacuum. The zero modes about the bounce solution that are
associated with the breaking of continuous internal symmetries result in an
enhancement of the tunneling rate into vacua in which some of the symmetries of
the initial state are spontaneously broken. We develop a general formalism for
evaluating the effects of these zero modes on the bubble nucleation rate in
both flat and curved space-times.Comment: LaTex, 11 pages, No figures, one minor chang
A posteriori agreement as a quality measure for readability prediction systems
All readability research is ultimately concerned with the research question whether it is possible for a prediction system to automatically determine the level of readability of an unseen text. A significant problem for such a system is that readability might depend in part on the reader. If different readers assess the readability of texts in fundamentally different ways, there is insufficient a priori agreement to justify the correctness of a readability prediction system based on the texts assessed by those readers. We built a data set of readability assessments by expert readers. We clustered the experts into groups with greater a priori agreement and then measured for each group whether classifiers trained only on data from this group exhibited a classification bias. As this was found to be the case, the classification mechanism cannot be unproblematically generalized to a different user group
Mass of perfect fluid black shells
The spherically symmetric singular perfect fluid shells are considered for
the case of their radii being equal to the event horizon (the black shells). We
study their observable masses, depending at least on the three parameters,
viz., the square speed of sound in the shell, instantaneous radial velocity of
the shell at a moment when it reaches the horizon, and integration constant
related to surface mass density. We discuss the features of black shells
depending on an equation of state.Comment: 1 figure, LaTeX; final version + FA
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