Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron Scattering Study of Quantum Phase Transitions in Integral Spin
  Chains   Quite a few low-dimensional magnets are quantum-disordered ``spin liquids''
with a characteristic gap in the magnetic excitation spectrum. Among these are
antiferromagnetic chains of integer quantum spins. Their generic feature are
long-lived massive (gapped) excitations (magnons) that are subject to Zeeman
splitting in external magnetic fields. The gap in one of the magnon branches
decreases with field, driving a soft-mode quantum phase transition. The system
then enters a qualitatively new high-field phase. The actual properties at high
fields, particularly the spin dynamics, critically depend on the system under
consideration. Recent neutron scattering studies of organometallic polymer
crystals NDMAP (Haldane spin chains with anisotropy) and NTENP (dimerized S=1
chains) revealed rich and unique physics.

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The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th