Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Hall conductivity in the frustrated pyrochlore magnet Tb2Ti2O7   In a ferromagnet, the spin excitations are the well-studied magnons. In
frustrated quantum magnets, long-range magnetic order fails to develop despite
a large exchange coupling between the spins. In contrast to the magnons in
conventional magnets, their spin excitations are poorly understood. Are they
itinerant or localized? Here we show that the thermal Hall conductivity
$\kappa_{xy}$ provides a powerful probe of spin excitations in the "quantum
spin ice" pyrochlore Tb$_2$Ti$_2$O$_7$. The thermal Hall response is large even
though the material is transparent. The Hall response arises from spin
excitations with specific characteristics that distinguish them from magnons.
At low temperature ($T<$ 1 K), the thermal conductivity imitates that of a
dirty metal. Using the Hall angle, we construct a phase diagram showing how the
excitations are suppressed by a magnetic field.

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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: physics
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an