Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vortex ratchet reversal at fractional matching fields in kagom\'e-like
  array with symmetric pinning centers   Arrays of Ni nanodots embedded in Nb superconducting films have been
fabricated by sputtering and electron beam lithography techniques. The arrays
are periodic triangular lattices of circular Ni dots arranged in a
kagom\'e-like pattern with broken reflection symmetry. Relevant behaviors are
found in the vortex lattice dynamics : i) At values lower than the first
integer matching field, several fractional matching fields are present when the
vortex lattice moves parallel or perpendicular to the reflection symmetry axis
of the array showing a clear anisotropic character in the magnetoresistance
curves, ii) injecting an ac current perpendicular to the reflection symmetry
axis of the array yields an unidirectional motion of the vortex lattice
(ratchet effect) as a result of the interaction between the whole vortex
lattice and the asymmetric lattice of dots, iii) increasing the input current
amplitudes the ratchet effect changes polarity independently of matching field
values. These experimental results can be explained taking into account the
vortex lattice density.

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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: plasm-ph