Surface and electronic structure at atomic length scales of the nonsymmorphic antiferromagnet Eu5In2Sb6

We performed scanning tunneling microscopy and spectroscopy (STM/STS) measurements to investigate the Zintl phase ${\mathrm{Eu}}₅{\mathrm{In}}₂{\mathrm{Sb}}₆$, a nonsymmorphic antiferromagnet. The theoretical prediction of a nontrivial Fermi surface topology stabilized by the nonsymmorphic symmetry motivated our research. On the cleaved (010) plane, we obtained striped patterns that can be correlated to the stacking of the [${\mathrm{In}}₂{\mathrm{Sb}}₆{]}^{10\ensuremath{-}}$ double chains along the crystallographic $c$ axis. The attempted cleavage along the $a$ axis revealed a more complex pattern. We combined the STS measurement on nonreconstructed (010) and (081) surfaces with DFT calculations to further elucidate the electronic structure of ${\mathrm{Eu}}₅{\mathrm{In}}₂{\mathrm{Sb}}₆$. From our investigations so far, direct experimental evidence of the predicted topological surface states remains elusive.