Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetically tunable Dirac and Weyl fermions in the Zintl materials
  family   Recent classification efforts encompassing crystalline symmetries have
revealed rich possibilities for solid-state systems to support a tapestry of
exotic topological states. However, finding materials that realize such states
remains a daunting challenge. Here we show how the interplay of topology,
symmetry, and magnetism combined with doping and external electric and magnetic
field controls can be used to drive the previously unreported SrIn$_2$As$_2$
materials family into a variety of topological phases. Our first-principles
calculations and symmetry analysis reveal that SrIn$_2$As$_2$ is a dual
topological insulator with $Z_2=(1;000)$ and mirror Chern number $C_M= -1$. Its
isostructural and isovalent antiferromagnetic cousin EuIn$_2$As$_2$ is found to
be an axion insulator with $Z_4= 2$. The broken time-reversal symmetry via Eu
doping in Sr$_{1-x}$Eu$_x$In$_2$As$_2$ results in a higher-order or topological
crystalline insulator state depending on the orientation of the magnetic easy
axis. We also find that antiferromagnetic EuIn$_2$P$_2$ is a trivial insulator
with $Z_4= 0$, and that it undergoes a magnetic field-driven transition to an
ideal Weyl fermion or nodal fermion state with $Z_4= 1$ with applied magnetic
field. Our study identifies Sr$_{1-x}$Eu$_x$In$_2$(As, P)$_2$ as a new tunable
materials platform for investigating the physics and applications of Weyl and
nodal fermions in the scaffolding of crystalline and axion insulator states.

19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an