Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electronic and structural properties of RbCeX$_2$ (X$_2$: O$_2$, S$_2$,
  SeS, Se$_2$, TeSe, Te$_2$)   Triangular lattice delafossite compounds built from magnetic lanthanide ions
are a topic of recent interest due to their frustrated magnetism and
realization of quantum disordered magnetic ground states. Here we report the
evolution of the structure and electronic ground states of RbCe$X_2$ compounds,
built from a triangular lattice of Ce$^{3+}$ ions, upon varying their anion
character ($X_2$= O$_2$, S$_2$, SeS, Se$_2$, TeSe, Te$_2$). This includes the
discovery of a new member of this series, RbCeO$_2$, that seemingly realizes a
quantum disordered ground state. Magnetization and susceptibility measurements
reveal that all compounds manifest mean-field antiferromagnetic interactions
and, with the exception of the oxide, possess a magnetic ordering transition
below 1 K. The crystalline electric field level scheme is explored via neutron
scattering and ab initio calculations to model the intramultiplet splitting of
the $J=5/2$ component. In addition to the two excited doublets expected from
the $J=5/2$ multiplet, we observe one extra, local mode present across the
sample series. This added mode shifts downward in energy with increasing anion
mass, suggesting a long-lived, vibronic state endemic to anion vibrations about
the Ce$^{3+}$ moments.

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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg