Interfacial coherency and ferroelectricity of BaTi O3 SrTi O3 superlattice films

We studied the phase transitions, domain morphologies, and polarizations in BaTi O3 SrTi O3 superlattices grown on SrTi O3 substrates. Using the phase field approach, we discovered the remarkable influence of film/substrate interfacial coherency on the ferroelectricity of the SrTi O3 layers within a superlattice: it is an orthorhombic ferroelectric for an incoherent interface while it exhibits only induced polarization by the adjacent BaTi O3 layers for a coherent interface. We presented the domain morphologies within individual BaTi O3 and SrTi O3 layers which have different ferroelectric symmetries. The results are compared to ultraviolet Raman spectroscopy and variable temperature x-ray diffraction measurements.