Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Room-temperature magnetic topological semimetal state in half-metallic
  Heusler Co$_2$TiX (X=Si, Ge, or Sn)   Topological semimetals (TSMs) including Weyl semimetals and nodal-line
semimetals are expected to open the next frontier of condensed matter and
materials science. Although the first inversion breaking Weyl semimetal was
recently discovered in TaAs, its magnetic counterparts, i.e., the time-reversal
breaking Weyl and nodal line semimetals, remain elusive. They are predicted to
exhibit exotic properties distinct from the inversion breaking TSMs including
TaAs. In this paper, we identify the magnetic topological semimetal state in
the ferromagnetic half-metal compounds Co$_2$TiX (X=Si, Ge, or Sn) with Curie
temperatures higher than 350 K. Our first-principles band structure
calculations show that, in the absence of spin-orbit coupling, Co$_2$TiX
features three topological nodal lines. The inclusion of spin-orbit coupling
gives rise to Weyl nodes, whose momentum space locations can be controlled as a
function of the magnetization direction. Our results not only open the door for
the experimental realization of topological semimetal states in magnetic
materials at room temperatures, but also suggest potential applications such as
unusual anomalous Hall effects in engineered monolayers of the Co$_2$TiX
compounds at high temperatures.

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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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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: mtrl-th