Electronic states and self-doping at a 45^o YBa2Cu3O7 grain boundary

TL;DR

This study uses first principles calculations to analyze charge redistribution and electronic states at a 45° grain boundary in YBa2Cu3O7, explaining transport suppression and self-doping effects relevant for superconductor applications.

Contribution

It provides a detailed, quantitative analysis of charge transfer and electronic state modifications at a specific grain boundary in YBa2Cu3O7, linking theory with experimental observations.

Findings

Charge redistribution is strongly inhomogeneous.

Self-doping of 0.10 holes per Cu atom occurs.

Transport across the grain boundary is suppressed.

Abstract

The charge redistribution at grain boundaries determines the applicability of high-Tc superconductors in electronic devices, because the transport across the grains can be hindered considerably. We investigate the local charge transfer and the modification of the electronic states in the vicinity of the grain-grain interface by first principles calculations for a (normal-state) 45^o tilted [001] grain boundary in YBa2Cu3O7. Our results explain the suppressed interface transport and the influence of grain boundary doping in a quantitative manner, in accordance with the experimental situation. The charge redistribution is found to be strongly inhomogeneous, which has a substantial effect on transport properties since it gives rise to a self-doping of 0.10 (+/- 0.02) holes per Cu atom.