Polaronic distortion and vacancy-induced magnetism in MgO

TL;DR

This study uses advanced density functional theory methods to investigate Mg vacancies in MgO, revealing the importance of strong correlation effects for accurate electronic structure predictions and implications for vacancy-induced magnetism.

Contribution

It demonstrates that functionals accounting for strong correlation effects correctly predict localized states, challenging previous delocalized predictions and constraining ferromagnetism in MgO.

Findings

Semilocal functionals predict delocalized states, inconsistent with experiments.

Hybrid and self-interaction corrected functionals predict localized states.

Results provide constraints on ferromagnetism in hole-doped MgO.

Abstract

The electronic structure of the neutral and singly charged Mg vacancy in MgO is investigated using density functional theory. For both defects, semilocal exchange correlation functionals such as the local spin density approximation incorrectly predict a delocalized degenerate ground state. In contrast functionals that take strong correlation effects into account predict a localized solution, in agreement with spin resonance experiments. Our results, obtained with the HSE hybrid, atomic self-interaction corrected and LDA+U functionals, provide a number of constraints to the possibility of ferromagnetism in hole doped MgO.