Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-orbit coupling and crystal-field splitting in Ti-doped Ca2RuO4
  studied by ellipsometry   In Ca2RuO4, the competition of spin-orbit coupling $\zeta$ and tetragonal
crystal field splitting $\Delta_{CF}$ has been discussed controversially for
many years. The orbital occupation depends on $\Delta_{CF}/\zeta$, which allows
us to address this ratio via the optical spectral weights of the lowest
intersite Mott-Hubbard excitations. We study the optical conductivity of
Ca$_2$Ru$_{0.99}$Ti$_{0.01}$O$_4$ in the range of 0.75 - 5 eV by ellipsometry,
using the large single crystals that can be grown for small Ti concentrations.
Based on a local multiplet calculation, our analysis results in $2.4 \leq
\Delta_{CF}/\zeta \leq 4$ at 15 K. The dominant crystal field yields a ground
state close to xy orbital order but spin-orbit coupling is essential for a
quantitative description of the properties. Furthermore, we observe a
pronounced decrease of $\Delta_{CF}$ with increasing temperature, as expected
based on the reduction of octahedral distortions.

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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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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: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: math
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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: cs
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The categories of this paper are: nlin
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The categories of this paper are: solv-int