Nanoscale self-templating for oxide epitaxy with large symmetry mismatch

Direct observations using scanning transmission electron microscopy unveil an intriguing interfacial bi-layer that enables epitaxial growth of a strain-free, monoclinic, bronze-phase VO(2)(B) thin film on a perovskite SrTiO(3) (STO) substrate. We observe an ultrathin (2–3 unit cells) interlayer best described as highly strained VO(2)(B) nanodomains combined with an extra (Ti,V)O(2) layer on the TiO(2) terminated STO (001) surface. By forming a fully coherent interface with the STO substrate and a semi-coherent interface with the strain-free epitaxial VO(2)(B) film above, the interfacial bi-layer enables the epitaxial connection of the two materials despite their large symmetry and lattice mismatch.