Imprint phenomenon of ferroelectric switching characteristics in BaTiO3/PbTiO3 multilayer thin films

Abstract

Materialsin which ferroelectric polarization can be locally controlled have potential for high-density information storage applications. Herein, we investigated the ferroelectric polarization switching characteristics of epitaxial BaTiO3/PbTiO3 (BTO/PTO) multilayer thin films by using piezoresponse force microscopy. Pulsed laser deposition was used to form an epitaxial BTO layer on an epitaxial ferroelectric PTO single thin film. This epitaxial BTO/PTO multilayer thin film exhibited an imprint phenomenon, in which the internal electric field was asymmetrically induced and the ferroelectric hysteresis loop was shifted. Owing to this imprint phenomenon, a large difference occurred between the two coercive electric fields of the ferroelectric hysteresis loop. Because the coercive electric field was reduced in one direction, a relatively small switching voltage was required to form ferroelectric polarization nanobits in a local region and the size of the switched nanobits was minimized. This behavior can be utilized as the basis for developing high-density ferroelectric-based storage media.