Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Microscopic phase diagram of LaFeAsO single crystals under pressure   We investigated LaFeAsO single crystals by means of synchrotron M\"ossbauer
spectroscopy under pressures up to 7.5 GPa and down to 13 K and provide a
microscopic phase diagram. We found a continuous suppression of the magnetic
hyperfine field with increasing pressure and it completely vanishes at $\sim$
7.5 GPa which is in contrast to the behavior in polycrystalline samples where
the magnetic order vanishes at $\sim$ 20 GPa. The different behavior of the
polycrystalline samples might be due to As-vacancies. Our results are in
qualitative agreement with density functional theory calculations where a
reduction of the magnetic moment with increasing pressure was found. We found
that among different samples at ambient pressure the magnetic phase transition
temperature as well as the low-temperature magnetic hyperfine field decrease
with increasing unit cell volume.

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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an