Direct Observation of an Interface Dipole between Two Metallic Oxides Caused by Localized Oxygen Vacancies

TL;DR

This study reveals that localized oxygen vacancies at metallic oxide interfaces induce a measurable interface dipole, demonstrated through advanced microscopy, spectroscopy, and theoretical calculations, highlighting atomic-scale structural mapping as a diagnostic tool.

Contribution

The paper provides direct experimental and theoretical evidence linking oxygen vacancies to interface dipoles in metallic oxides, advancing understanding of interfacial phenomena.

Findings

Oxygen vacancies cause cation displacements at the interface.

Displacements indicate a dipole-like electric field despite metallicity.

Structural mapping can detect oxygen vacancies at interfaces.

Abstract

Oxygen vacancies are increasingly recognized to play a role in phenomena observed at transition-metal oxide interfaces. Here we report a study of SrRuO3/La0.7Sr0.3MnO3 (SRO/LSMO) interfaces using a combination of quantitative aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and density-functional calculations. Cation displacements are observed at the interface, indicative of a dipole-like electric field even though both materials are nominally metallic. The observed displacements are reproduced by theory if O vacancies are present in the near-interface LSMO layers. The results suggest that atomic-scale structural mapping can serve as a quantitative indicator of the presence of O vacancies at interfaces.