21,362 research outputs found
Dynamic magnetic response of infinite arrays of ferromagnetic particles
Recently developed techniques to find the eigenmodes of a ferromagnetic
particle of arbitrary shape, as well as the absorption in the presence of an
inhomogeneous radio-frequency field, are extended to treat infinite lattices of
such particles. The method is applied to analyze the results of recent FMR
experiments, and yields substantially good agreement between theory and
experiment
Is U3Ni3Sn4 best described as near a quantum critical point?
Although most known non-Fermi liquid (NFL) materials are structurally or
chemically disordered, the role of this disorder remains unclear. In
particular, very few systems have been discovered that may be stoichiometric
and well ordered. To test whether U3Ni3Sn4 belongs in this latter class, we
present measurements of the x-ray absorption fine structure (XAFS) of
polycrystalline and single-crystal U3Ni3Sn4 samples that are consistent with no
measurable local structural disorder. We also present temperature-dependent
specific heat data in applied magnetic fields as high as 8 T that show features
that are inconsistent with the antiferromagnetic Griffiths' phase model, but do
support the conclusion that a Fermi liquid/NFL crossover temperature increases
with applied field. These results are inconsistent with theoretical
explanations that require strong disorder effects, but do support the view that
U3Ni3Sn4 is a stoichiometric, ordered material that exhibits NFL behavior, and
is best described as being near an antiferromagnetic quantum critical point.Comment: 9 pages, 8 figures, in press with PR
Belief heterogeneity and survival in incomplete markets
In complete markets economies (Sandroni [16]), or in economies with Pareto optimal outcomes (Blume and Easley [10]), the market selection hypothesis holds, as long as traders have identical discount factors. Traders who survive must have beliefs that merge with the truth. We show that in incomplete markets, regardless of tradersâ discount factors, the market selects for a range of beliefs, at least some of which do not merge with the truth. We also show that impatient traders with incorrect beliefs can survive and that these incorrect beliefs impact prices. These beliefs may be chosen so that they are far from the truth
Tuning electronic structures via epitaxial strain in Sr2IrO4 thin films
We have synthesized epitaxial Sr2IrO4 thin-films on various substrates and
studied their electronic structures as a function of lattice-strains. Under
tensile (compressive) strains, increased (decreased) Ir-O-Ir bond-angles are
expected to result in increased (decreased) electronic bandwidths. However, we
have observed that the two optical absorption peaks near 0.5 eV and 1.0 eV are
shifted to higher (lower) energies under tensile (compressive) strains,
indicating that the electronic-correlation energy is also affected by in-plane
lattice-strains. The effective tuning of electronic structures under
lattice-modification provides an important insight into the physics driven by
the coexisting strong spin-orbit coupling and electronic correlation.Comment: 9 pages, 5 figures, 1 tabl
The eclipsing X-ray pulsar X-7 in M33
Using our extensive ROSAT X-ray observations of M33, we confirm a 3.45 day
eclipse period for the Einstein source X-7 (Larson & Schulman, 1997) and
discover evidence for a 0.31-s pulse period. The orbital period, pulse period
and observed X-ray luminosity are remarkably similar to SMC X-1. We therefore
suggest M33 X-7 is a neutron star high mass X-ray binary with a 15-40 Msol O/B
companion and a binary separation of 25-33 Rsol if the companion is almost
filling its Roche lobe.Comment: accepted for publication in MNRA
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