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 ${\mathrm{SrTiO}}_{3}$(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 ${\mathrm{Cu}}_{3}\mathrm{N}$(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 $\mathrm{FeSe}\text{/}{\mathrm{Cu}}_{3}\mathrm{N}$ interface, strong magnetic frustration between the dimer and stripe antiferromagnetic states may exist in the FeSe monolayer. According to the charge transfer analysis, the ${\mathrm{Cu}}_{3}\mathrm{N}$ substrate can dope $\ensuremath{\sim}0.02$ 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 $\mathrm{FeSe}\text{/}{\mathrm{Cu}}_{3}\mathrm{N}$ 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 $\mathrm{FeSe}\text{/}{\mathrm{SrTiO}}_{3}$.