Chemically synthesized metal–oxide–metal segmented nanowires with high ferroelectric response

A chemical synthesis method is presented for the fabrication of high-definition segmented metal–oxide–metal (MOM) nanowires in two different ferroelectric oxide systems: Au–BaTiO₃–Au and Au–PbTiO₃–Au. This method entails electrodeposition of segmented nanowires of Au–TiO₂–Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO₂ segments into BaTiO₃ or PbTiO₃ segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.