514 research outputs found
Comment on "Effects of Point Defects on the Phase Diagram of Vortex States in High-Tc Superconductors in the B || c Axis"
We comment on a recent work by Nonomura and Hu who simulated the 3D XY model
for a type-II superconductor in an applied magnetic field, in the presence of
uncorrelated point randomness. We clarify the nature of the "vortex slush"
state that they found, and argue that this state is unstable in the
thermodynamic limit.Comment: 2 pages, 2 figure
Statistics of Conserved Quantities in Mechanically Stable Packings of Frictionless Disks Above Jamming
We numerically simulate mechanically stable packings of soft-core,
frictionless, bidisperse disks in two dimensions, above the jamming packing
fraction . For configurations with a fixed isotropic global stress
tensor, we compute the averages, variances, and correlations of conserved
quantities (stress , force-tile area , Voronoi
volume , number of particles , and number of small
particles ) on compact subclusters of particles , as a
function of the cluster size and the global system stress. We find several
significant differences depending on whether the cluster is defined
by a fixed radius or a fixed number of particles . We comment on the
implications of our findings for maximum entropy models of jammed packings.Comment: 11 pages, 19 figure
Glassiness, Rigidity and Jamming of Frictionless Soft Core Disks
The jamming of bi-disperse soft core disks is considered, using a variety of
different protocols to produce the jammed state. In agreement with other works,
we find that cooling and compression can lead to a broad range of jamming
packing fractions , depending on cooling rate and initial
configuration; the larger the degree of big particle clustering in the initial
configuration, the larger will be the value of . In contrast, we find
that shearing disrupts particle clustering, leading to a much narrower range of
as the shear strain rate varies. In the limit of vanishingly small
shear strain rate, we find a unique non-trivial value for the jamming density
that is independent of the initial system configuration. We conclude that shear
driven jamming is a unique and well defined critical point in the space of
shear driven steady states. We clarify the relation between glassy behavior,
rigidity and jamming in such systems and relate our results to recent
experiments.Comment: 10 pages, 11 figures, significantly expanded version as accepted for
publication in PR
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