Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Repeated deterministic defect-assisted switching of magnetic vortex core
  polarity   Because of its stability, the polarity of a magnetic vortex core (VC) is a
candidate for binary data storage. Switching can be accomplished, e.g, by
driving the VC above a critical velocity $v_c$. Here, we report on controlled
and repeated switching of VC polarity by significantly reducing $v_c$ locally.
We excite vortex dynamics in thin Permalloy disks with a magnetic field pulse,
and map the two-dimensional VC trajectory using time-resolved Kerr microscopy.
In pristine samples, we observe normal gyrotropic motion of the VC. After
laser-induced generation of defects, however, we observe repeated VC reversal
at much-reduced critical velocities as low as 20 m/s. Micromagnetic simulations
reveal how local reduction of exchange coupling can create VC reversal sites
for deterministic VC switching.

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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: q-alg
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-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: nlin