Do Se vacancies electron dope monolayer FeSe?

TL;DR

This study investigates how selenium vacancies affect electron doping in monolayer FeSe, revealing that they act more like hole dopants and do not account for observed electron pockets.

Contribution

It demonstrates that Se vacancies do not serve as electron dopants but instead induce hole doping, challenging previous assumptions about their role in FeSe superconductivity.

Findings

Se vacancies create a vacancy-centered orbital below the Fermi level.

Disorder broadening causes effective hole doping.

Se vacancies do not explain large electron pockets in ARPES.

Abstract

Following the discovery of the potentially very high temperature superconductivity in monolayer FeSe we investigate the doping effect of Se vacancies in these materials. We find that Se vacancies pull a vacancy centered orbital below the Fermi energy that absorbs most of the doped electrons. Furthermore we find that the disorder induced broadening causes an effective hole doping. The surprising net result is that in terms of the band structure Se vacancies behave like hole dopants rather than electron dopants. Our results exclude Se vacancies as the origin of the large electron pockets measured by angle resolved photoemission spectroscopy.