The enhanced ferroelectricity in Sr1-δTiO3/BaTiO3 superlattices with Sr deficiency

Abstract

Here we report the tunable ferroelectricity in superlattices of (Sr1-delta TiO3)(n)/(BaTiO3)(8) with delta & x224d; 5% and the maximally enhanced ferroelectricity is found in the n= 6 superlattice. The room-temperature remnant polarization of n =6 is enhanced by 70% and 1120% compared to those of BaTiO3 and Sr1-delta TiO3 thin films, respectively. The ferroelectric transition temperature of n =6 is 40 K higher than that of the BaTiO3 film, and is independent of the measurement frequency. The dependence of remnant field 2P(r) on n coincides well with the n dependence of gamma/alpha, which is ratio between out-of-plane and in-plane octahedral rotation angles. It thus suggests a strong correlation between the octahedral rotation pattern and the ferroelectric distortion. Our study demonstrates the importance of constructing superlattices to enhance the ferroelectric properties of the defect-engineered materials to be better than the pristine materials.