Ferroelectric properties of LaAlO3∕BaTiO3 superlattices prepared by laser molecular-beam epitaxy

LaAl O 3 ∕ BaTi O 3 superlattices were obtained on (100)-oriented Nb-doped SrTiO3 substrates by laser molecular-beam epitaxy. The x-ray diffraction spectra indicated that the c-axis strain changed with the layer thickness of the superlattices. The relation of the ferroelectric properties to the strain was studied with the different stacking periodicity at a fixed periodic number. The results showed that the strains played an important role on remnant polarization. The maximum remanent polarization was obtained at the highest c-axis strain stacking periodicity of 4∕4. The use of a LaAlO3 cap layer enhanced the ferroelectric properties due to the restricted strain effect.