  The synthesis of thin films of magnetic topological materials is necessary to
achieve novel quantized Hall effects and electrodynamic responses. EuIn2As2 is
a recently predicted topological axion insulator that has an antiferromagnetic
ground state and an inverted band structure, but that has only been synthesized
and studied as a single crystal. We report on the synthesis of c-axis oriented
EuIn2As2 films on sapphire substrates by molecular beam epitaxy. By carefully
tuning the substrate temperature during growth, we stabilize the Zintl phase of
EuIn2As2 expected to be topologically non-trivial. The magnetic properties of
these films reproduce those seen in single crystals, but their resistivity is
enhanced when grown at lower temperatures. We additionally find that the
magnetoresistance of EuIn2As2 is negative even up to fields as high as 31T.
while it is highly anisotropic at low fields, it becomes nearly isotropic at
high magnetic fields above 5T. Overall, the transport characteristics of
EuIn2As2 appear similar to those of chalcogenide topological insulators,
motivating the development of devices to gate tune the Fermi energy and reveal
topological features in quantum transport.
