52 research outputs found
The viscous slowing down of supercooled liquids as a temperature-controlled superArrhenius activated process: a description in terms of frustration-limited domains
We propose that the salient feature to be explained about the glass
transition of supercooled liquids is the temperature-controlled superArrhenius
activated nature of the viscous slowing down, more strikingly seen in
weakly-bonded, fragile systems. In the light of this observation, the relevance
of simple models of spherically interacting particles and that of models based
on free-volume congested dynamics are questioned. Finally, we discuss how the
main aspects of the phenomenology of supercooled liquids, including the
crossover from Arrhenius to superArrhenius activated behavior and the
heterogeneous character of the relaxation, can be described by an
approach based on frustration-limited domains.Comment: 13 pages, 4 figures, accepted in J. Phys.: Condensed Matter,
proceedings of the Trieste workshop on "Unifying Concepts in Glass Physics
Instability of charge ordered states in doped antiferromagnets
We analyze the induced interactions between localized holes in weakly-doped
Heisenberg antiferromagnets due to the modification of the quantum zero point
spin wave energy; i.e. the analogue of the Casimir effect. We show that this
interaction is uniformly attractive and falls off as r^{-2 d+1} in d
dimensions. For ``stripes'', i.e parallel (d-1)-dimensional hypersurfaces of
localized holes, the interaction energy per unit hyperarea is attractive and
falls, generically, like r^{-d}. We argue that, in the absence of a long-range
Coulomb repulsion between holes, this interaction leads to an instability of
any charge-ordered state in the dilute doping limit.Comment: Revtex, 5 pages two-column format, 3 ps figures (epsf). Two
references added and some textual change
An implementation plan for priorities in solar-system space physics
The scientific objectives and implementation plans and priorities of the Space Science Board in areas of solar physics, heliospheric physics, magnetospheric physics, upper atmosphere physics, solar-terrestrial coupling, and comparative planetary studies are discussed and recommended programs are summarized. Accomplishments of Skylab, Solar Maximum Mission, Nimbus-7, and 11 other programs are highlighted. Detailed mission plans in areas of solar and heliospheric physics, plasma physics, and upper atmospheric physics are also described
Quantum critical fluctuations in an Fe-based superconductor
Quantum critical fluctuations may prove to play an instrumental role in the formation of unconventional superconductivity. Here, we show that the characteristic scaling of a marginal Fermi liquid is present in inelastic light scattering data of an Fe-based superconductor tuned through a quantum critical point (QCP) by chemical substitution or doping. From the doping dependence of the imaginary time dynamics we are able to distinguish regions dominated by quantum critical behavior from those having classical critical responses. This dichotomy reveals a connection between the marginal Fermi liquid behavior and quantum criticality. In particular, the overlap between regions of high superconducting transition temperatures and quantum critical scaling suggests a contribution from quantum fluctuations to the formation of superconductivity
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Quantum critical fluctuations in an Fe-based superconductor
Quantum critical fluctuations may prove to play an instrumental role in the formation of unconventional superconductivity. Here, we show that the characteristic scaling of a marginal Fermi liquid is present in inelastic light scattering data of an Fe-based superconductor tuned through a quantum critical point (QCP) by chemical substitution or doping. From the doping dependence of the imaginary time dynamics we are able to distinguish regions dominated by quantum critical behavior from those having classical critical responses. This dichotomy reveals a connection between the marginal Fermi liquid behavior and quantum criticality. In particular, the overlap between regions of high superconducting transition temperatures and quantum critical scaling suggests a contribution from quantum fluctuations to the formation of superconductivity
Translational Symmetry Breaking in the Superconducting State of the Cuprates: Analysis of the Quasiparticle Density of States
Motivated by the recent STM experiments of J.E. Hoffman et.al. and C. Howald
et.al., we study the effects of weak translational symmetry breaking on the
quasiparticle spectrum of a d-wave superconductor. We develop a general
formalism to discuss periodic charge order, as well as quasiparticle scattering
off localized defects. We argue that the STM experiments in
cannot be explained using a simple charge density
wave order parameter, but are consistent with the presence of a periodic
modulation in the electron hopping or pairing amplitude. We review the effects
of randomness and pinning of the charge order and compare it to the impurity
scattering of quasiparticles. We also discuss implications of weak
translational symmetry breaking for ARPES experiments.Comment: 12 pages, 9 figs; (v2) minor corrections to formalism, discussions of
dispersion, structure factors and sum rules added; (v3) discussion of
space-dependent normalization added. To be published in PR
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