Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical Analysis of Single-ion Anisotropy in d$^3$ Mott Insulators   An effective spin model for Mott insulators is determined by the symmetries
involved among magnetic sites, electron fillings, and their interactions. Such
a spin Hamiltonian offers insight to mechanisms of magnetic orders and magnetic
anisotropy beyond the Heisenberg model. For a spin moment S bigger than 1/2,
single-ion anisotropy is in principle allowed. However, for $d^3$ Mott
insulators with large cubic crystal field splitting, the single-ion anisotropy
is absent within the LS coupling, despite S=3/2 local moment. On the other
hand, preferred magnetic moment directions in $d^3$ materials have been
reported which calls for a further theoretical investigation. Here we derive
the single-ion anisotropy interaction using the strong-coupling perturbation
theory. The cubic crystal field splitting including $e_g$ orbtals, trigonal
distortions, Hund's coupling, and spin-orbit coupling beyond the LS scheme are
taken into account. For compressed distortion, the spin-orbit coupling at
magnetic sites favors the easy-plane while that of anions leads to easy-axis
anisotropy. We apply the theory on $\rm{CrX}_3$ with X = Cl and I, and show the
dependence of the single-ion anisotropy on the ratio of the spin-orbit
couplings of magnetic and anion sites. Significance of the single-ion
anisotropy in ideal two-dimensional magnets is also discussed.

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The categories of this paper are: cs
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The categories of this paper are: math
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
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The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex