Epitaxial TiOx Surface in Ferroelectric BaTiO3: Native Structure and Dynamic Patterning at the Atomic Scale

TL;DR

This study uncovers the atomic-scale structure of BaTiO3 surfaces, revealing a native TiOx layer and demonstrating high-resolution patterning via electron-beam irradiation to induce surface phase transitions.

Contribution

It combines advanced microscopy and thermodynamics to characterize ferroelectric surfaces and introduces a scalable method for nanoscale surface patterning and functionalization.

Findings

Native TiOx layer identified on BaTiO3 surface

Sub-nanometer resolution patterning achieved with electron-beam

Surface phase transitions driven by electron-beam irradiation

Abstract

Surfaces and interfaces of ferroelectric oxides exhibit enhanced functionality, and therefore serve as a platform for novel nano and quantum technologies. Experimental and theoretical challenges associated with examining the subtle electro-chemo-mechanical balance at metal-oxide surfaces have hindered the understanding and control of their structure and behavior. Here, we combine advanced electron-microscopy and first-principles thermodynamics methods to reveal the atomic-scale chemical and crystallographic structure of the surface of the seminal ferroelectric BaTiO3. We show that the surface is composed of a native < 2-nm thick TiOx rock-salt layer in epitaxial registry with the BaTiO3. Using electron-beam irradiation, we successfully patterned artificially TiOx sites with sub-nanometer resolution, by inducing Ba escape. Therefore, our work offers electro-chemo-mechanical insights into ferroelectric surface behavior in addition to a method for scalable high-resolution beam-induced chemical lithography for selectively driving surface phase transitions, and thereby functionalizing metal-oxide surfaces.