First-principles study of magnetic frustration in FeSe epitaxial films on SrTiO$_3$

TL;DR

This study uses first-principles calculations to explore how electron doping and phonon vibrations induce magnetic frustration in monolayer and bilayer FeSe films on SrTiO$_3$, aligning with experimental observations.

Contribution

It reveals the mechanisms of magnetic frustration induced by doping and vibrations in FeSe films, highlighting layer-dependent effects and interface electron accumulation.

Findings

Doping and phonons induce magnetic frustration in monolayer FeSe.

Electron doping causes layer-specific magnetic effects in bilayer FeSe.

Results agree with experimental data on FeSe/SrTiO$_3$ systems.

Abstract

The effects of electron doping and phonon vibrations on the magnetic properties of monolayer and bilayer FeSe epitaxial films on SrTiO$_3$ have been studied, respectively, using first-principles calculations with van der Waals correction. For monolayer FeSe epitaxial film, the combined effect of electron doping and phonon vibrations readily leads to magnetic frustration between the collinear antiferromagnetic state and the checkerboard antiferromagnetic N\'eel state. For bilayer FeSe epitaxial film, such magnetic frustration is much more easily induced by electron doping in its bottom layer than its top layer. The underlying physics is that the doped electrons are accumulated at the interface between the FeSe layers and the substrate. These results are consistent with existing experimental studies.