Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Record-Breaking Magnetoresistance at the Edge of a Microflake of Natural
  Graphite   Placing several electrodes at the edge of a micrometer-size Sri Lankan
natural graphite sample at distances comparable to the size of the internal
crystalline regions, we found record values for the change of the resistance
with magnetic field. At low temperatures and at $B \sim 21$T the
magnetoresistance (MR) reaches $\sim 10^7$%. The MR values exceed by far all
earlier reported ones for graphite and they are comparable or even larger (at
$T > 50$K) than the largest reported in solids including the Weyl semimetals.
The origin of this large MR lies in the existence of highly conducting 2D
interfaces aligned parallel to the graphene planes.

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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
2
The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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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: cmp-lg
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The categories of this paper are: math-ph
3
The categories of this paper are: physics
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph