Dynamic defect correlations dominate activated electronic transport in SrTiO3

TL;DR

This paper reveals that in SrTiO3, defect complexes with dynamic correlations, rather than independent point defects, dominate the photo-activated electronic transport, highlighting the importance of defect interactions in complex oxides.

Contribution

It demonstrates that defect complexes with dynamic correlations govern electronic transport in SrTiO3, challenging models based on independent point defects.

Findings

Defect complexes significantly influence persistent photoconductivity.

Transport behavior cannot be explained by independent point defect models.

Dynamic defect correlations are crucial for understanding electronic properties.

Abstract

Strontium titanate (SrTiO3, STO) is a critically important material for the study of emergent electronic phases in complex oxides, as well as for the development of applications based on their heterostructures. Despite the large body of knowledge on STO, there are still many uncertainties regarding the role of defects in the properties of STO, including their influence on ferroelectricity in bulk STO and ferromagnetism in STO-based heterostructures. We present a detailed analysis of the decay of persistent photoconductivity in STO single crystals with defect concentrations that are relatively low but significantly affect their electronic properties. The results show that photo-activated electron transport cannot be described by a superposition of the properties due to independent point defects as current models suggest but is, instead, governed by defect complexes that interact through dynamic correlations. These results emphasize the importance of defect correlations for activated electronic transport properties of semiconducting and insulating perovskite oxides.