Interfacial intermixing in $\delta$-doped oxide superlattices

First principles studies of the interfaces between dissimilar insulating oxides have been fundamental in understanding both the origin of emergent interfacial phenomena and ways to control conduction pathways and charge carrier densities. However, these calculations often assume sharp interfaces; neglecting the effects of interfacial cation intermixing. Using density functional theory, we examine the effect of $A$-site interfacial intermixing on the stability and electronic structure of oxide $\delta$-doped heterointerfaces. We find that the dominant effect of interfacial intermixing is the reduction in carrier densities of the 2DEG states at the interface. Our previous work suggest that this reduction in carrier density (i.e. fractional $\delta$-doping) may lead to enhancements in electron mobilities. These results offer a plausible explanation for the deviations in carrier mobilities and densities measured in different experimental samples. Furthermore, our calculations show that intermixing above 1/4 concentration is unstable relative to a clean interface; thus having implications for large scale production, where experimental growth techniques, such as chemical vapor deposition, may be a viable alternative.