Ferroelastically protected polarization switching pathways to control electrical conductivity in strain-graded ferroelectric nanoplates

Abstract

Controllable local electronic conduction in otherwise insulating materials can be created by arranging two opponent ferroelectric polarizations in a head to head (or tail to tail) configuration. Using an effective trailing field of dc biased tip motion, charged domain walls have been artificially created in the context of tip-based nanolithography. However, the charged domain wall formed by a trailing field is unstable because of elastic interaction at the boundary between poling and nonpoling regions, finally resulting in ferroelastic back-switching. Here, we report that nanoscale plate structures under strain relaxation can provide a promising opportunity for stabilization and manipulation of a charged domain wall using a highly anisotropic mechanical boundary condition that restricts the unique ferroelastic domain configuration. We demonstrate that a ferroelectric BiFeO3 nanoplate subjected to compressive misfit strain at the bottom but less external stress on the side walls exhibits radial-quadrant in-plane ferroelectric domain structures. Electronic conduction is significantly enhanced near the side walls and the magnitude of electrostatic conductivity is adjustable up to about 20 times by 180 degrees ferroelectric switching that is protected by the clamped ferroelastic domain. Our findings provide a pathway to controllable nanoelectronic logic devices by tuning a charged ferroelectric domain wall.