Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Soft phonons reveal the nematic correlation length in
  Ba(Fe$_{0.94}$Co$_{0.06}$)$_2$As$_2$   Nematicity is ubiquitous in electronic phases of high-$T_c$ superconductors,
particularly in the Fe-based systems. While several experiments have probed
nematic fluctuations, they have been restricted to uniform or momentum averaged
fluctuations. Here, we investigate the behavior of finite-momentum nematic
fluctuations by utilizing the anomalous softening of acoustic phonon modes in
optimally doped Ba(Fe$_{0.94}$Co$_{0.06}$)$_2$As$_2$. We determine the nematic
correlation length and find that it sharply changes its $T$-dependence at
$T_c$, revealing a strong connection between nematicity and superconductivity.

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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: q-bio