19,370 research outputs found
Absence of structural correlations of magnetic defects in heavy fermion LiV2O4
Magnetic defects have pronounced effects on the magnetic properties of the
face-centered cubic compound LiV2O4. The magnetic defects arise from crystal
defects present within the normal spinel structure. High-energy x-ray
diffraction studies were performed on LiV2O4 single crystals to search for
superstructure peaks or any other evidence of periodicity in the arrangement of
the crystal defects present in the lattice. Entire reciprocal lattice planes
are mapped out with help of synchrotron radiation. No noticeable differences in
the x-ray diffraction data between a crystal with high magnetic defect
concentration and a crystal with low magnetic defect concentration have been
found. This indicates the absence of any long-range periodicity or short-range
correlations in the arrangements of the crystal/magnetic defects.Comment: 6 pages, 4 figure
Non-abelian resonance: product and coproduct formulas
We investigate the resonance varieties attached to a commutative differential
graded algebra and to a representation of a Lie algebra, with emphasis on how
these varieties behave under finite products and coproducts.Comment: 12 page
Valence Quark Distribution in A=3 Nuclei
We calculate the quark distribution function for 3He/3H in a relativistic
quark model of nuclear structure which adequately reproduces the nucleon
approximation, nuclear binding energies, and nuclear sizes for small nuclei.
The results show a clear distortion from the quark distribution function for
individual nucleons (EMC effect) arising dominantly from a combination of
recoil and quark tunneling effects. Antisymmetrization (Pauli) effects are
found to be small due to limited spatial overlaps. We compare our predictions
with a published parameterization of the nuclear valence quark distributions
and find significant agreement.Comment: 18pp., revtex4, 4 fig
Semi-regular masas of transfinite length
In 1965 Tauer produced a countably infinite family of semi-regular masas in
the hyperfinite factor, no pair of which are conjugate by an
automorphism. This was achieved by iterating the process of passing to the
algebra generated by the normalisers and, for each , finding
masas for which this procedure terminates at the -th stage. Such masas are
said to have length . In this paper we consider a transfinite version of
this idea, giving rise to a notion of ordinal valued length. We show that all
countable ordinals arise as lengths of semi-regular masas in the hyperfinite
factor. Furthermore, building on work of Jones and Popa, we
obtain all possible combinations of regular inclusions of irreducible
subfactors in the normalising tower.Comment: 14 page
Dissipation, topology, and quantum phase transition in a one-dimensional Joesphson junction array
We study the phase diagram and quantum critical properties of a resistively
shunted Josephson junction array in one dimension from a strong coupling
analysis. After mapping the dissipative quantum phase model to an effective
sine-Gordon model we study the renormalization group flow and the phase
diagram. We try to bridge the phase diagrams obtained from the weak and the
strong coupling renormalization group calculations to extract a more
comprehensive picture of the complete phase diagram. The relevance of our
theory to experiments in nanowires is discussed.Comment: 13 pages, 3 figures, A few typos are correcte
Superconducting quantum phase transitions tuned by magnetic impurity and magnetic field in ultrathin a-Pb films
Superconducting quantum phase transitions tuned by disorder (d), paramagnetic
impurity (MI) and perpendicular magnetic field (B) have been studied in
homogeneously disordered ultrathin a-Pb films. The MI-tuned transition is
characterized by progressive suppression of the critical temperature to zero
and a continuous transition to a weakly insulating normal state with increasing
MI density. In all important aspects, the d-tuned transition closely resembles
the MI-tuned transition and both appear to be fermionic in nature. The B-tuned
transition is qualitatively different and probably bosonic. In the critical
region it exhibits transport behavior that suggests a B-induced mesoscale phase
separation and presence of Cooper pairing in the insulating state.Comment: 17 pages, 4 figure
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