A Three Component Self-Assembled Epitaxial Nanocomposite Thin Film

A self-assembled three phase epitaxial nanocomposite film is grown consisting of approximate to 3 nm diameter fcc metallic Cu nanorods within square prismatic SrO rocksalt nanopillars in a Sr(Ti,Cu)O3- perovskite matrix. Each phase has an epitaxial relation to the others. The core-shell-matrix structures are grown on SrTiO3 substrates and can also be integrated onto Si using a thin SrTiO3 buffer. The structure is made by pulsed laser deposition in vacuum from a SrTi0.75Cu0.25O3 target, and formed as a result of the limited solubility of Cu in the perovskite matrix. Wet etching removes the 3 nm diameter Cu nanowires leaving porous SrO pillars. The three-phase nanocomposite film is used as a substrate for growing a second epitaxial nanocomposite consisting of CoFe2O4 spinel pillars in a BiFeO3 perovskite matrix, producing dramatic effects on the structure and magnetic properties of the CoFe2O4. This three-phase vertical nanocomposite provides a complement to the well-known two-phase nanocomposites, and may offer a combination of properties of three different materials as well as additional avenues for strain-mediated coupling within a single film.