Configurable Crack Wall Conduction in a Complex Oxide.

Yeo, Youngki; Hwang, Soo-Yoon; Yeo, Jinwook; Kim, Jihun; Jang, Jinhyuk; Park, Heung-Sik; Kim, Yong-Jin; Le, Duc Duy et al. · Nano Lett · 2023

basic_science · Level V

Where this comes from

Abstract

Mobile defects in solid-state materials play a significant role in memristive switching and energy-efficient neuromorphic computation. Techniques for confining and manipulating point defects may have great promise for low-dimensional memories. Here, we report the spontaneous gathering of oxygen vacancies at strain-relaxed crack walls in SrTiO<sub>3</sub> thin films grown on DyScO<sub>3</sub> substrates as a result of flexoelectricity. We found that electronic conductance at the crack walls was enhanced compared to the crack-free region, by a factor of 10<sup>4</sup>. A switchable asymmetric diode-like feature was also observed, and the mechanism is discussed, based on the electrical migration of oxygen vacancy donors in the background of Sr-deficient acceptors forming n<sup><i>+</i></sup>-n or n<i>-</i>n<sup><i>+</i></sup> junctions. By tracing the temporal relaxations of surface potential and lattice expansion of a formed region, we determine the diffusivity of mobile defects in crack walls to be 1.4 × 10<sup>-16</sup> cm<sup>2</sup>/s, which is consistent with oxygen vacancy kinetics.