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

摘要

We investigated the ferroelectric properties of strontium titanate (STO) thinfilms deposited on SrTiO3 (001) substrate with SrRuO3 electrodes. The STO layerwas grown coherently on the SrTiO3 substrate without in-plane latticerelaxation, but its out-of-plane lattice constant increased with a decrease inthe oxygen pressure during deposition. Using piezoresponse force microscopy andP-V measurements, we showed that our tetragonal STO films possessroom-temperature ferroelectricity. We discuss the possible origins of theobserved ferroelectricity.