Ferroelectric Oxide Thin Film with an Out-of-Plane Electrical Conductivity

Ferroelectricity and electrical conductivity are two fundamentally incompatible properties that are difficult to simultaneously achieve in a material. Here, we combine these two contradictory properties by embedding conducting SrNbO₃ micro/nanopillars into a ferroelectric SrNbO_3.5 (i.e., Sr₂Nb₂O₇) thin film. The high-T_c ferroelectric SrNbO_3.5 thin film is epitaxially grown on a LaAlO₃ substrate by pulsed laser deposition. The conducting SrNbO₃ micro/nanopillars are introduced into the film via an electron-irradiation-induced SrNbO_3.5-to-SrNbO₃ phase transformation triggered by a focused electron beam. The sizes and distribution of the SrNbO₃ micro/nanopillars can be accurately controlled through artificial manipulation of the electron-irradiation-induced SrNbO_3.5-to-SrNbO₃ phase transformation. The ferroelectric SrNbO₃/SrNbO_3.5 thin film with an in-plane polarization exhibits an electrical conductivity in the out-of-plane direction. Such conducting ferroelectric thin films may lead to the discovery of plentiful physical phenomena and have great potential for pyroelectric, photoelectric, and multiferroic applications.