All-Oxide Metasurfaces Formed by Synchronized Local Ionic Gating.

Ionic gating of oxide thin films has emerged as a novel way of manipulating the properties of thin films. Most studies have been carried out on single devices with a three-terminal configuration but, by exploring the electrokinetics during the ionic gating, such a configuration with initially insulating films leads to a highly non-uniform gating response of individual devices within large arrays of the devices. We show that such an issue can be circumvented by the formation of a uniform charge potential by the use of a thin conducting underlayer. This synchronized local ionic gating allows for the simultaneous manipulation of the electrical, magnetic, and/or optical properties of large arrays of devices. Designer metasurfaces formed in this way from SrCoO 2.5 thin films display anomalous optical reflection of light that relies on the uniform and coherent response of all the devices. Beyond oxides, almost any material whose properties can be controlled by the addition or removal of ions via gating can form novel metasurfaces using this technique. Our findings provide insights into the electrokinetics of ionic gating and a wide range of applications using synchronized local ionic gating. This article is protected by copyright. All rights reserved.