Self-assembling behavior and interface structure in vertically aligned nanocomposite (Pr_0.5Ba_0.5MnO₃)_1-x:(CeO₂)_x...

Heteroepitaxial oxide-based nanocomposite films possessing a variety of functional properties have attracted tremendous research interest. Here, self-assembled vertically aligned nanocomposite (Pr_0.5Ba_0.5MnO₃)_1-x:(CeO₂)_x (x = 0.2 and 0.5) films have been successfully grown on single-crystalline (001) (La,Sr)(Al,Ta)O₃ substrates by the pulsed laser deposition technique. Self-assembling behavior of the nanocomposite films and atomic-scale interface structure between Pr_0.5Ba_0.5MnO₃ matrix and CeO₂ nanopillars have been investigated by advanced electron microscopy techniques. Two different orientation relationships, (001)[100]_{Pr0.5Ba0.5MnO3}//(001)[1-10]_CeO2 and (001)[100]_{Pr0.5Ba0.5MnO3}//(110)[1-10]_CeO2, form between Pr_0.5Ba_0.5MnO₃ and CeO₂ in the (Pr_0.5Ba_0.5MnO₃)_0.8:(CeO₂)_0.2 film along the film growth direction, which is essentially different from vertically aligned nanocomposite (Pr_0.5Ba_0.5MnO₃)_0.5:(CeO₂)_0.5 films having only (001)[100]_{Pr0.5Ba0.5MnO3}//(001)[1-10]_CeO2 orientation relationship. Both coherent and semi-coherent Pr_0.5Ba_0.5MnO₃/CeO₂ interface appear in the films. In contrast to semi-coherent interface with regular distribution of interfacial dislocations, interface reconstruction occurs at the coherent Pr_0.5Ba_0.5MnO₃/CeO₂ interface. Our findings indicate that epitaxial strain imposed by the concentration of CeO₂ in the nanocomposite films affects the self-assembling behavior of the vertically aligned nanocomposite (Pr_0.5Ba_0.5MnO₃)_1-x:(CeO₂)_x films.