Local Ferroelectricity in SrTiO_3 Thin Films

TL;DR

This study reveals local ferroelectricity in SrTiO_3 thin films at temperatures above the dielectric permittivity maximum, using confocal microscopy to explore inhomogeneous polarization behaviors and phase coexistence.

Contribution

It demonstrates the presence of local ferroelectric phases in SrTiO_3 thin films at high temperatures, highlighting the importance of local probes in ferroelectric research.

Findings

Identification of homogeneous out-of-plane and inhomogeneous in-plane ferroelectric phases.

Observation of both hysteretic and non-hysteretic responses under dc bias.

Detection of local ferroelectricity above the dielectric maximum temperature.

Abstract

The temperature-dependent polarization of SrTiO_3 thin films is investigated using confocal scanning optical microscopy. A homogeneous out-of-plane and inhomogeneous in-plane ferroelectric phase are identified from images of the linear electrooptic response. Both hysteretic and non-hysteretic behavior are observed under a dc bias field. Unlike classical transitions in bulk ferroelectrics, local ferroelectricity is observed at temperatures far above the dielectric permittivity maximum. The results demonstrate the utility of local probe experiments in understanding inhomogeneous ferroelectrics.