Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Strain Derivatives of $T_c$ in HgBa$_2$CuO$_{4+\delta}$: CuO$_2$
  Plane Alone is Not Enough   The strain derivatives of $T_c$ along the $a$ and $c$ axes have been
determined for HgBa$_2$CuO$_{4+\delta}$ (Hg1201), the simplest monolayer
cuprate with the highest $T_c$ of all monolayer cuprates ($T_c$ = 97 K at
optimal doping). The underdoped compound with the initial $T_c$ of 65 K has
been studied as a function of pressure up to 20 GPa by magnetic susceptibility
and X-ray diffraction (XRD). The observed linear increase in $T_c$ with
pressure is the same as previously been found for the optimally-doped compound.
The above results have enabled the investigation of the origins of the
significantly different $T_c$ values of optimally doped Hg1201 and the
well-studied compound La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO), the latter value of
$T_c$ = 40 K being only about 40% of the former. Hg1201 can have almost
identical CuO$_6$ octahedra as LSCO if specifically strained. When the apical
and in-plane CuO$_2$ distances are the same for the two compounds, a large
discrepancy in their $T_c$ remains. Differences in crystal structures and
interactions involving the Hg-O charge reservoir layers of Hg1201 may be
responsible for the different $T_c$ values exhibited by the two compounds.

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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: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-lat