  We performed Scanning Tunneling Microscopy and Spectroscopy (STM/STS)
measurements to investigate the Zintl phase Eu$_5$In$_2$Sb$_6$, a
non-symmorphic antiferromagnet. The theoretical prediction of a non-trivial
Fermi surface topology stabilized by the non-symmorphic symmetry motivated our
research. On the cleaved (010) plane, we obtained striped patterns that can be
correlated to the stacking of the [In$_2$Sb$_6$]$^{10-}$ 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
non-reconstructed (010) and (081) surfaces with DFT calculations to further
elucidate the electronic structure of Eu$_5$In$_2$Sb$_6$. From our
investigations so far, direct experimental evidence of the predicted
topological surface states remains elusive.
