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

Abstract

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 SrNbO3.5 (i.e., Sr2Nb2O7) thin film. The high-T c ferroelectric SrNbO3.5 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 SrNbO3.5-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 SrNbO3.5-to-SrNbO3 phase transformation. The ferroelectric SrNbO3/SrNbO3.5 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.

Review on Recent Developments in 2D Ferroelectrics: Theories and Applications

“…In addition to the combination of in‐plane metallicity and out‐of‐plane ferroelectricity, the coexistence of out‐of‐plane metallicity and in‐plane ferroelectricity was recently realized in SrNbO 3 micro/nanopillars‐embedded ferroelectric SrNbO 3.5 (i.e., Sr 2 Nb 2 O 7 ) thin film (Figure 9b). [ 73 ] The conducting SrNbO 3 micro/nanopillars result from an electron‐irradiation‐induced SrNbO 3.5 ‐to‐SrNbO 3 phase transformation triggered by a focused electron beam. This novel method may inspire researchers to design 2D ferroelectrics that simultaneously possessing out‐of‐plane metallicity and in‐plane ferroelectricity.…”