Observation of room-temperature ferroelectricity in tetragonal strontium titanate thin films on SrTiO3 (001) substrates

TL;DR

This study demonstrates that tetragonal strontium titanate thin films grown on SrTiO3 substrates exhibit ferroelectricity at room temperature, with properties influenced by oxygen pressure during deposition.

Contribution

First demonstration of room-temperature ferroelectricity in tetragonal STO thin films on SrTiO3 substrates with detailed analysis of growth conditions.

Findings

Room-temperature ferroelectricity observed in tetragonal STO films

Ferroelectric properties depend on oxygen pressure during growth

Lattice constant increases as oxygen pressure decreases

Abstract

We investigated the ferroelectric properties of strontium titanate (STO) thin films deposited on SrTiO3 (001) substrate with SrRuO3 electrodes. The STO layer was grown coherently on the SrTiO3 substrate without in-plane lattice relaxation, but its out-of-plane lattice constant increased with a decrease in the oxygen pressure during deposition. Using piezoresponse force microscopy and P-V measurements, we showed that our tetragonal STO films possess room-temperature ferroelectricity. We discuss the possible origins of the observed ferroelectricity.