Gapping of Dirac surface states through time reversal symmetry breaking may realize the axion insulator state in condensed matter. Despite tremendous efforts, only a few material systems fall in this category of intrinsic magnetic topological insulators (TI). Recent theoretical calculations proposed the antiferromagnetic EuIn2As2 to be a topologically non-trivial magnetic insulator with gapped surface states. Here we use scanning tunneling microscopy and spectroscopy (STM/STS) complemented with density-functional theory (DFT) calculations and modelling to probe the surface electronic states in EuIn2As2. We find a spin-orbit induced bulk gap of ~120 meV located only a few meV above the Fermi energy, within which topological surface states reside. Temperature dependent measurements provide evidence of the partial gapping (~40 meV) of the surface states at low temperatures below the AFM order, which decreases with increasing temperature but remains finite above TN
@article{arxiv.2209.09972,
title = {Surface state evolution induced by magnetic order in axion insulator candidate EuIn2As2},
author = {Mingda Gong and Divyanshi Sar and Joel Friedman and Dariusz Kaczorowski and S. Abdel Razek and Wei-Cheng Lee and Pegor Aynajian},
journal= {arXiv preprint arXiv:2209.09972},
year = {2022}
}
Comments
8 pages, 8 figures, to be published in Physical Review B