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

Yao, Tingting; Jiang, Yixiao; Chen, Chunlin; Yan, Xuexi; Tao, Ang; Yang, Lixin; Li, Cuihong; Sugo, Kenyu et al. · Nano Lett · 2020

basic_science · Level V

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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 SrNbO<sub>3</sub> micro/nanopillars into a ferroelectric SrNbO<sub>3.5</sub> (i.e., Sr<sub>2</sub>Nb<sub>2</sub>O<sub>7</sub>) thin film. The high-<i>T</i><sub>c</sub> ferroelectric SrNbO<sub>3.5</sub> thin film is epitaxially grown on a LaAlO<sub>3</sub> substrate by pulsed laser deposition. The conducting SrNbO<sub>3</sub> micro/nanopillars are introduced into the film via an electron-irradiation-induced SrNbO<sub>3.5</sub>-to-SrNbO<sub>3</sub> phase transformation triggered by a focused electron beam. The sizes and distribution of the SrNbO<sub>3</sub> micro/nanopillars can be accurately controlled through artificial manipulation of the electron-irradiation-induced SrNbO<sub>3.5</sub>-to-SrNbO<sub>3</sub> phase transformation. The ferroelectric SrNbO<sub>3</sub>/SrNbO<sub>3.5</sub> 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.