Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exotic low-energy excitations emergent in the random Kitaev magnet
  Cu$_2$IrO$_3$   We report on magnetization $M(H)$, dc/ac magnetic susceptibility $\chi(T)$,
specific heat $C_{\mathrm{m}}(T)$ and muon spin relaxation ($\mu$SR)
measurements of the Kitaev honeycomb iridate Cu$_2$IrO$_2$ with quenched
disorder. In spite of the chemical disorders, we find no indication of spin
glass down to 260~mK from the $C_{\mathrm{m}}(T)$ and $\mu$SR data.
Furthermore, a persistent spin dynamics observed by the zero-field muon spin
relaxation evidences an absence of static magnetism. The remarkable observation
is a scaling relation of $\chi[H,T]$ and $M[H,T]$ in $H/T$ with the scaling
exponent $\alpha=0.26-0.28$, expected from bond randomness. However,
$C_{\mathrm{m}}[H,T]/T$ disobeys the predicted universal scaling law, pointing
towards the presence of low-lying excitations in addition to random singlets.
Our results signify an intriguing role of quenched disorder in a Kitaev spin
system in creating low-energy excitations possibly pertaining to Z$_2$ fluxes.

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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
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The categories of this paper are: hep-th
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph