Effect of monolayer registration on the band structure of FeSe/SrTiO₃

Interface and surface phenomena are intrinsically linked in bulk-2D heterostructures such as monolayer FeSe / SrTiO₃. The registration of the two-dimensional film with respect to the substrate is consequently no less important to the properties of the system than the presence of defects and/or impurities at the interface. We present density functional theory calculations in which we calculate the energies and electronic structures of FeSe / SrTiO₃ heterostructures with different sources of electron doping and exhibiting different registrations of the FeSe monolayer. We find that the most stable registration corresponds to that which has been observed in superconducting FeSe / SrTiO₃ samples, and in this configuration the unfolded band structure of the system is consistent with experimental ARPES data, namely the disruption and near-removal of the Γ-centered hole pocket.