Control of surface potential at polar domain walls in a nonpolar oxide

TL;DR

This paper demonstrates control over the surface potential at polar domain walls in nonpolar calcium titanate, revealing potential for novel nanoelectronic devices utilizing polar domain walls in ferroelastic materials.

Contribution

It provides the first evidence of electrostatic control of domain-wall polarization in nonpolar ferroelastic oxides, enabling potential device applications.

Findings

Macroscopic resonances indicate piezoelectric response from polar walls

Surface potential at domain walls can be modulated by electron injection

Polar domain walls influence local surface potential in CaTiO3

Abstract

Ferroic domain walls could play an important role in microelectronics, given their nanometric size and often distinct functional properties. Until now, devices and device concepts were mostly based on mobile domain walls in ferromagnetic and ferroelectric materials. A less explored path is to make use of polar domain walls in nonpolar ferroelastic materials. Indeed, while the polar character of ferroelastic domain walls has been demonstrated, polarization control has been elusive. Here, we report evidence for the electrostatic signature of the domain-wall polarization in nonpolar calcium titanate (CaTiO3). Macroscopic mechanical resonances excited by an ac electric field are observed as a signature of a piezoelectric response caused by polar walls. On the microscopic scale, the polarization in domain walls modifies the local surface potential of the sample. Through imaging of surface potential variations, we show that the potential at the domain wall can be controlled by electron injection. This could enable devices based on nondestructive information readout of surface potential.