Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photonic Topological Transitions and Epsilon-Near-Zero Surface Plasmons
  in Type-II Dirac Semimetal NiTe$_2$   Compared to artificial metamaterials, where nano-fabrication complexities and
finite-size inclusions can hamper the desired electromagnetic response, several
natural materials like van der Waals crystals hold great promise for designing
efficient nanophotonic devices in the optical range. Here, we investigate the
unusual optical response of NiTe$_2$, a van der Waals crystal and a type-II
Dirac semimetal hosting Lorentz-violating Dirac fermions. By {\it ab~initio~}
density functional theory modeling, we show that NiTe$_2$ harbors multiple
topological photonic regimes for evanescent waves (such as surface plasmons)
across the near-infrared and optical range. By electron energy-loss
experiments, we identify surface plasmon resonances near the photonic
topological transition points at the epsilon-near-zero (ENZ) frequencies
$\approx 0.79$, $1.64$, and $2.22$ eV. Driven by the extreme crystal anisotropy
and the presence of Lorentz-violating Dirac fermions, the experimental evidence
of ENZ surface plasmon resonances confirm the non-trivial photonic and
electronic topology of NiTe$_2$. Our study paves the way for realizing devices
for light manipulation at the deep-subwavelength scales based on electronic and
photonic topological physics for nanophotonics, optoelectronics, imaging, and
biosensing applications.

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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
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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: q-bio