Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unusual Behaviour of (Np,Pu)B2C   Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized
by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were
determined from single crystal X-ray data to be isotypic with the ThB2C-type
(space group R3m, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a =
0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z=9). Physical properties have been
derived from polycrystalline bulk material in the temperature range from 2 K to
300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat
capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C
with a Neel temperature T_N = 68 K. PuB2C is a Pauli paramagnet most likely due
to a strong hybridisation of s(p,d) electrons with the Pu-5f states. A
pseudo-gap, as concluded from the Sommerfeld value and the electronic
transport, is thought to be a consequence of the hybridisation. The magnetic
behaviour of {Np,Pu}B2C is consistent with the criterion of Hill.

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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: physics