Site-specific fabrication and epitaxial conversion of functional oxide nanodisk arrays

Nanodisk arrays of technologically important magnetic (CoFe(2)O(4)) and ferroelectric (BaTiO(3)) oxides are fabricated on diverse substrates with well-defined size and separation using the soft-eBL approach. We demonstrate that below a certain pattern size, the as-deposited amorphous nanodisks can be readily converted into dense, single-crystal form that exhibit cube-on-cube heteroepitaxy with respect to the underlying single-crystal substrate. Such single-crystal disks show well-defined truncated-pyramid morphology that is consistent with Wulff construction. The mechanism of morphology development with the pattern size change is discussed. Localized characterization of the crystallinity, chemical composition, and magnetic behavior of the CFO nanodisk patterns are carried out using analytical transmission electron microscopy and magnetic force microscopy. Such solution-based epitaxial conversion of patterned arrays of multifunctional oxides has potential for viable cost-effective technological applications.