Structural, Vibrational, and Dielectric Properties of BiFeO3/LaFeO3 Superlattices Grown on (001)-SrTiO3

BiFeO₃/LaFeO₃ (BFO/LFO) epitaxial superlattices (SLs) with different bilayer thicknesses were grown via pulsed laser deposition on a (001)-SrTiO₃ substrate buffered with a SrRuO₃ bottom electrode. Room-temperature X-ray diffraction demonstrated strong structural changes in tuning the bilayer thickness while keeping the total thickness constant. Superlattices with thin periods were characterized by an antiferroelectric Pnma-like phase, while thick bilayers of the SLs were more likely to be described by a mixed state, including a rhombohedral ferroelectric bulk-like phase. Raman scattering analysis further confirmed the structural behaviour deduced by X-ray diffraction. Strain relaxation and symmetry changes were moreover accompanied by modifications in the dielectric properties correlated with the deduced (anti)ferroic structural phases.