Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge-stripe order, antiferromagnetism, and spin dynamics in the
  cuprate-analog nickelate La$_4$Ni$_3$O$_8$   We report a muon spin rotation ($\mu$SR) study of the cuprate-analog
nickelate La$_4$Ni$_3$O$_8$, which undergoes a transition at 105 K to a
low-temperature phase with charge-stripe and antiferromagnetic (AFM) order on
square planar NiO$_2$ layers. Zero-field $\mu$SR shows that this transition is
abrupt and that the AFM configuration is commensurate. Comparison of observed
muon precession frequencies with Ni dipolar field calculations yields Ni
moments $\lesssim 0.5\mu_B$. Dynamic muon spin relaxation above 105 K suggests
critical slowing of Ni spin fluctuations, but is inconsistent with
corresponding $^{139}$La NMR results. Critical slowing and an abrupt transition
are also observed in the planar cuprate AFM La$_2$CuO$_{4+\delta}$, where they
are evidence for weakly interplanar-coupled two-dimensional AFM spin
fluctuations, but our $\mu$SR data do not agree quantitatively with theoretical
predictions for this scenario.

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The categories of this paper are: funct-an
3
The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
2
The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin