Structural Properties of Plastically Deformed SrTiO3 and KTaO3

TL;DR

This study investigates the structural effects of plastic deformation on SrTiO3 and KTaO3, revealing dislocation structures and local ferroelectric order that influence their electronic properties.

Contribution

It provides a comprehensive structural analysis of plastically deformed SrTiO3 and KTaO3 using advanced scattering techniques, highlighting their dislocation configurations and emergent ferroelectricity.

Findings

Dislocation configurations depend on strain and are characterized by diffuse scattering and NMR.

Local ferroelectric order is observed near dislocation walls in both materials.

KTaO3 is established as a second model system for studying defect-induced emergent physics.

Abstract

Dislocation engineering has the potential to open new avenues toward the exploration and modification of the properties of quantum materials. Strontium titanate (SrTiO3, STO) and potassium tantalate (KTaO3, KTO) are incipient ferroelectrics that show metallization and superconductivity at extremely low charge carrier concentrations, and have been the subject of resurgent interest. These materials also exhibit remarkable ambient-temperature ductility, and thus represent exceptional platforms for studies of the effects of deformation-induced dislocation structures on electronic properties. Recent work on plastically deformed STO revealed an enhancement of the superconducting transition temperature and the emergence of local ferroelectricity and magnetism near self-organized dislocation walls. Here we present a comprehensive structural analysis of plastically deformed STO and KTO, employing specially designed strain cells, diffuse neutron and x-ray scattering, Raman scattering, and nuclear magnetic resonance (NMR). Diffuse scattering and NMR provide insight into the dislocation configurations and densities and their dependence on strain. As in the prior work on STO, Raman scattering reveals evidence for local ferroelectric order near dislocation walls in plastically deformed KTO. Our findings provide valuable information about the self-organized defect structures in both materials, and they position KTO as a second model system with which to explore the associated emergent physics.