First-principles study on the electronic and magnetic properties of monolayer FeSe on Cu3N(001)

The significantly enhanced superconductivity in the FeSe monolayer on oxide substrates like SrTiO3(001), for which the electron doping from the substrate to the FeSe monolayer is considered a key factor, has attracted extensive interest in the past decade. Here, based on the first-principles electronic structure calculations, we propose that Cu3N(001) is a promising hole-doping substrate for tuning the electronic and magnetic properties of the epitaxially grown FeSe monolayer. Due to the in-plane lattice strain and the electron redistribution at the FeSe/Cu3N interface, strong magnetic frustration between the dimer and stripe antiferromagnetic states may exist in the FeSe monolayer. According to the charge transfer analysis, the Cu3N substrate can dope similar to 0.02 hole per Fe atom to the FeSe monolayer, and the hole doping level can be partially modulated by the external electric field and/or the Cu vacancies in the substrate. These results indicate that FeSe/Cu3N is a prospective platform for exploring the hole-doped superconductivity in the FeSe-based interfacial system, which may serve as a model system in contrast to electron-doped FeSe/SrTiO3.