In a common paradigm, the electronic structure of condensed matter is divided into weakly and strongly correlated compounds. While conventional band theory usually works well for the former class, many-body effects are essential for the latter. Materials such as the familiar ${\mathrm{SrTiO}}_3$ (STO) compound that bridge or even abandon this characterization scheme are highly interesting. Here, it is shown, by means of combining density functional theory with dynamical mean-field theory, that oxygen vacancies on the STO (001) surface give rise to a dichotomy of weakly correlated $t_{2g}$ low-energy quasiparticles and localized “in-gap” states of dominant $e_g$ character with a subtle correlation signature. We furthermore touch base with recent experimental work and study the surface instability towards magnetic order.

• Received 22 December 2015

DOI:https://doi.org/10.1103/PhysRevB.93.121103