MBE growth of axion insulator candidate EuIn2As2

TL;DR

This paper reports the successful synthesis of EuIn2As2 thin films via molecular beam epitaxy, demonstrating magnetic and transport properties consistent with topological axion insulators, paving the way for future quantum device applications.

Contribution

First synthesis of EuIn2As2 thin films on sapphire, confirming topological and magnetic properties similar to single crystals, and exploring their transport behavior under high magnetic fields.

Findings

EuIn2As2 films are stabilized in the Zintl phase during MBE growth.

Magnetoresistance remains negative up to 31T, with high anisotropy at low fields.

Transport properties resemble those of chalcogenide topological insulators.

Abstract

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.