Lattice dynamics and structural distortions in the multiferroic (Ba,Sr)TiO3/(Bi,Nd)FeO3 heterostructures

We report the synthesis, the structure and phonon spectra studies of epitaxial double-layer heterostructures consisting of Bi0.98Nd0.02FeO3 and Ba0.8Sr0.2TiO3 layers deposited on (100) MgO substrates. The results of x-ray diffraction and the polarization characteristics of Raman spectra suggest a monoclinic symmetry of the systems at room temperature. The observed spectra demonstrate the non-monotonous dependence on the layer thickness that apparently can be related with specificity of the light propagation in the layered thin-film systems.