12,762 research outputs found
Fate of the Peak Effect in a Type-II Superconductor: Multicriticality in the Bragg-Glass Transition
We have used small-angle-neutron-scattering (SANS) and ac magnetic
susceptibility to investigate the global magnetic field H vs temperature T
phase diagram of a single crystal Nb in which a first-order transition of
Bragg-glass melting (disordering), a peak effect, and surface superconductivity
are all observable. It was found that the disappearance of the peak effect is
directly related to a multicritical behavior in the Bragg-glass transition.
Four characteristic phase boundary lines have been identified on the H-T plane:
a first-order line at high fields, a mean-field-like continuous transition line
at low fields, and two continuous transition line associated with the onset of
surface and bulk superconductivity. All four lines are found to meet at a
multicritical point.Comment: 4 figure
Anticommutative extension of the Adler map
We construct a noncommutative (Grassmann) extension of the well-known Adler Yang–Baxter map. It satisfies the Yang–Baxter equation, it is reversible and birational. Our extension preserves all the properties of the original map except the involutivity
Einstein Equations and MOND Theory from Debye Entropic Gravity
Verlinde's proposal on the entropic origin of gravity is based strongly on
the assumption that the equipartition law of energy holds on the holographic
screen induced by the mass distribution of the system. However, from the theory
of statistical mechanics we know that the equipartition law of energy does not
hold in the limit of very low temperature. Inspired by the Debye model for the
equipartition law of energy in statistical thermodynamics and adopting the
viewpoint that gravitational systems can be regarded as a thermodynamical
system, we modify Einstein field equations. We also perform the study for
Poisson equation and modified Newtonian dynamics (MOND). Interestingly enough,
we find that the origin of the MOND theory can be understood from Debye
entropic gravity perspective. Thus our study may fill in the gap existing in
the literature understanding the theoretical origin of MOND theory. In the
limit of high temperature our results reduce to their respective standard
gravitational equations.Comment: 8 pages, no figures. Accepted for publication in JCA
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Polyisoprene Captured Sulfur Nanocomposite Materials for High-Areal-Capacity Lithium Sulfur Battery
A polyisoprene-sulfur (PIPS) copolymer and nano sulfur composite material (90 wt % sulfur) is synthesized through inverse vulcanization of PIP polymer with micrometer-sized sulfur particles for high-areal-capacity lithium sulfur batteries. The polycrystalline structure and nanodomain nature of the copolymer are revealed through high-resolution transmission electron microscopy (HRTEM). PIP polymer is also used as binders for the electrode to further capture the dissovlved polysulfides. A high areal capacity of ca. 7.0 mAh/cm2 and stable cycling are achieved based on the PIPS nanosulfur composite with a PIP binder, crucial to commercialization of lithium sulfur batteries. The chemical confinement both at material and electrode level alleviates the diffusion of polysulfides and the shuttle effect. The sulfur electrodes, both fresh and cycled, are analyzed through scanning electron microscopy (SEM). This approach enables scalable material production and high sulfur utilization at the cell level
Fe-doping induced superconductivity in charge-density-wave system 1T-TaS2
We report the interplay between charge-density-wave (CDW) and
superconductivity of 1-FeTaS ()
single crystals. The CDW order is gradually suppressed by Fe-doping,
accompanied by the disappearance of pseudogap/Mott-gap as shown by the density
functional theory (DFT) calculations. The superconducting state develops at low
temperatures within the CDW state for the samples with the moderate doping
levels. The superconductivity strongly depends on within a narrow range,
and the maximum superconducting transition temperature is 2.8 K as . We
propose that the induced superconductivity and CDW phases are separated in real
space. For high doping level (), the Anderson localization (AL) state
appears, resulting in a large increase of resistivity. We present a complete
electronic phase diagram of 1-FeTaS system that shows a
dome-like
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