Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The role of rare events in the pinning problem   Type II superconductors exhibit a fascinating phenomenology that is
determined by the dynamical properties of the vortex matter hosted by the
material. A crucial element in this phenomenology is vortex pinning by material
defects, e.g., immobilizing vortices at small drives and thereby guaranteeing
dissipation-free current flow. Pinning models for vortices and other
topological defects, such as domain walls in magnets or dislocations in
crystals, come in two standard variants: i) weak collective pinning, where
individual weak defects are unable to pin, while the random accumulation of
many force centers within a collective pinning volume combines into an
effective pin, and ii) strong pinning, where strong defects produce large
vortex displacements and bistabilities that lead to pinning on the level of
individual defects. The transition between strong and weak pinning is
quantified by the Labusch criterion $\kappa \approx f_p/\bar{C}\xi = 1$, where
$f_p$ and $\bar{C}$ are the force of one defect and the effective elasticity of
the vortex lattice, respectively ($\xi$ is the coherence length). Here, we show
that a third generic type of pinning becomes dominant when the pinning force
$f_p$ enters the weak regime, the pinning by rare events. We find that within
an intermediate regime $1/2 < \kappa < 1$, compact pairs of weak defects define
strong pinning clusters that extend the mechanism of strong pinning into the
weak regime. We present a detailed analysis of this cluster-pinning mechanism
and show that its pinning-force density parametrically dominates over the weak
pinning result. The present work is a first attempt to include correlations
between defects into the discussion of strong pinning.

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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg