Large out-of-plane ferroelectric polarization in flat epitaxial BaTiO3 on CoFe2O4 heterostructures

Engineering interfaces in perovskite/spinel heterostructures is challenged by structural differences. We have used kinetic growth limitations to fabricate flat BaTiO3/CoFe2O4 (BTO/CFO) epitaxial bilayers on La2/3Sr1/3MnO3/SrTiO3(001). In situ analysis of lattice strain during growth has revealed that BTO grows relaxed on highly lattice-mismatched CFO, thus suppressing tensile epitaxial stress effects. As a result, BTO is ferroelectric along the out-of-plane direction with bulk-like polarization. These results show that very high lattice mismatch in heteroepitaxy can be an opportunity rather than a limitation to integrate dissimilar materials with optimized functional properties. (C) 2013 AIP Publishing LLC.