Quantitative calculations of charge carrier densities in the depletion layers at YBa2Cu3O7-x interfaces

TL;DR

This paper uses ab-initio calculations to quantify charge carrier densities at YBa2Cu3O7-x interfaces, revealing inherent hole-underdoping and ways to tune doping via impurities and substitutions.

Contribution

It provides the first quantitative ab-initio analysis of charge redistribution and doping control at high-Tc superconductor interfaces.

Findings

Intrinsic hole-underdoping at clean interfaces

Cation substitution can compensate charge transfer

Impurities enable doping adjustment

Abstract

Charge redistribution at high-Tc superconductor interfaces and grain boundaries on the one hand is problematic for technological application. On the other hand, it gives rise to a great perspective for tailoring the local electronic states. For prototypical (metallic) interfaces, we derive quantitative results for the intrinsic doping of the CuO2-planes, i.e. for the deviation of the charge carrier density from the bulk value. Our data are based on ab-initio supercell calculations within density functional theory. A remarkable hole-underdoping is inherent to the clean interface, almost independent of the interface geometry. On the contrary, cation substitution as well as incorporation of electronegative impurities can compensate the intrinsic charge transfer and provide access to an exact adjustment of the superconductor's doping. The effects of oxygen deficiency are discussed.