Structural and electrical properties of self-assembled (BiFeO$_{3})_{0.5}$:(Sm$_{2}$O$_{3})_{0.5}$ nanocomposite films

Self-assembled (BiFeO$_{3})_{0.5}$:(Sm$_{2}$O$_{3})_{0.5}$ nanocomposite films were deposited on (001) SrTiO$_{3}$ and Nb-doped SrTiO$_{3}$ substrates by pulsed laser deposition using a single uniformly mixed target. Analysis from both high-resolution X-ray diffraction and transmission electron microscopy revealed self-assembled epitaxial two-phase BiFeO$_{3}$ (BFO) and Sm$_{2}$O$_{3}$ (SmO) composites in nanoscale. The BFO and SmO domains have grown alternately and vertically aligned with average column size of 10 nm. The dielectric properties of BFO:SmO nanocomposite films were investigated and compared with those of pure BFO and SmO thin films. The dielectric constant of the nanocomposites can be well described by a parallel connection of two individual dielectrics of BFO and SmO. On the other hand, the dielectric loss of nanocomposite films is lower than the theoretical value from such a parallel connection model. This might originate from the reduction of leakage current density of BFO phase in nanocomposite film due to the much larger interfacial area and the strong out-of-plane strain of each BFO column.