Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unusual magnetic field-induced phase transition in the mixed state of
  superconducting NbSe2   The thermal conductivity \kappa in the basal plane of single-crystalline
hexagonal NbSe2 has been measured as a function of magnetic field H, oriented
both along and perpendicular to the c-axis, at several temperatures below T_c.
With the magnetic field in the basal plane and oriented parallel to the heat
flux we observed, in fields well below H_c2, an unexpected hysteretic behavior
of \kappa(H) with all the generic features of a first order phase transition.
The transition is not manifest in the \kappa(H) curves, if H is still in the
basal plane but oriented perpendicularly to the heat-flux direction. The origin
of the transition is not yet understood.

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The categories of this paper are: stat
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph