Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropy, phonon modes, and free charge carrier parameters in
  monoclinic $\beta$-gallium oxide single crystals   We derive a dielectric function tensor model approach to render the optical
response of monoclinic and triclinic symmetry materials with multiple uncoupled
infrared and farinfrared active modes. We apply our model approach to
monoclinic $\beta$-Ga$_2$O$_3$ single crystal samples. Surfaces cut under
different angles from a bulk crystal, (010) and ($\bar{2}$01), are investigated
by generalized spectroscopic ellipsometry within infrared and farinfrared
spectral regions. We determine the frequency dependence of 4 independent
$\beta$-Ga$_2$O$_3$ Cartesian dielectric function tensor elements by matching
large sets of experimental data using a point by point data inversion approach.
From matching our monoclinic model to the obtained 4 dielectric function tensor
components, we determine all infared and farinfrared active transverse optic
phonon modes with $A_u$ and $B_u$ symmetry, and their eigenvectors within the
monoclinic lattice. We find excellent agreement between our model results and
results of density functional theory calculations. We derive and discuss the
frequencies of longitudinal optical phonons in $\beta$-Ga$_2$O$_3$. We derive
and report density and anisotropic mobility parameters of the free charge
carriers within the tin doped crystals. We discuss the occurrence of
longitudinal phonon plasmon coupled modes in $\beta$-Ga$_2$O$_3$ and provide
their frequencies and eigenvectors. We also discuss and present monoclinic
dielectric constants for static electric fields and frequencies above the
reststrahlen range, and we provide a generalization of the Lyddane-Sachs-Teller
relation for monoclinic lattices with infrared and farinfrared active modes. We
find that the generalized Lyddane-Sachs-Teller relation is fulfilled
excellently for $\beta$-Ga$_2$O$_3$.

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The categories of this paper are: atom-ph
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
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The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
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The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
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The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: math