Antifferomagnetic FeSe monolayer on SiTiO${}_3$: The charge doping and electric field effects

Abstract

We present theoretically the electronic structure of antiferromagnetic (AFM) FeSe monolayer on TiO${}_2$ terminated SrTiO${}_3$(001) surface. It is revealed that the striking disappearance of the Fermi surface around the Brillouin zone (BZ) center can be well explained by the antiferromatnetic (AFM) phase. We show that the system has a considerable charge transfer from SrTiO${}_3$(001) substrate to FeSe monolayer, and so has a self-constructed electric field. The FeSe monolayer band structure near the BZ center is sensitive to charge doping, and the spin-resolved energy bands at BZ corner are distorted to be flattened by the perpendicular electric field. We propose a tight-binding model Hamiltonian to take these key factors into account. We also show that this composite structure is an ideal electron-hole bilayer system, with electrons and holes respectively formed in FeSe monolayer and TiO${}_2$ surface layer.

12 pages, 6 figures