Raman and X-ray diffraction study of (Ba,Sr)TiO3/(Bi,Nd)FeO3 multilayer heterostructures

We report synthesis, X-ray diffraction (XRD) and Raman scattering characterisation of epitaxial heterostructures containing alternating (Bi0.98Nd0.02)FeO3 (BNFO) and (Ba0.8Sr0.2TiO3) (BST) layers deposited on (100) MgO substrates. A significant shift of the BST soft mode and partial depolarisation in the Raman spectra of multilayer heterostructures caused by epitaxial strains were observed. Satellite peaks typical for superlattices were observed in the XRD patterns of multilayer heterostructures with layer thicknesses below 30 nm. Raman spectra of the BNFO/BST superlattice with a modulation period of 10 nm revealed hardening of the soft mode and a dominating symmetric-stretching mode at 705 cm− 1 due to distortion in FeO6 octahedra enforced by the epitaxial strain in the superlattice.