A Three Component Self‐Assembled Epitaxial Nanocomposite Thin Film

Abstract

A self‐assembled three phase epitaxial nanocomposite film is grown consisting of ≈3 nm diameter fcc metallic Cu nanorods within square prismatic SrO rocksalt nanopillars in a Sr(Ti,Cu)O 3‐ δ perovskite matrix. Each phase has an epitaxial relation to the others. The core–shell‐matrix structures are grown on SrTiO 3 substrates and can also be integrated onto Si using a thin SrTiO 3 buffer. The structure is made by pulsed laser deposition in vacuum from a SrTi 0.75 Cu 0.25 O 3 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 CoFe 2 O 4 spinel pillars in a BiFeO 3 perovskite matrix, producing dramatic effects on the structure and magnetic properties of the CoFe 2 O 4 . 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.