Harnessing Electrostructural Bistability to Control Defects in Polarizable Materials

Abstract

Structural defects are central to the functionalities of materials. However, conventional approaches to defect control are often slow and imprecise. This work identifies and characterizes a distinct physical phenomenon of electrostructural bistability that provides a rapid and precise pathway for engineering materials with defect-controlled physical properties. A generalized theory of conductivity bistability is developed and experimentally validated to unify two distinct regimes: previously reported electrothermal bistability in weakly polarizable insulators, such as silicon, and electrostructural bistability in strongly polarizable materials, such as TiO$_2$. In agreement with the theory, experiments on TiO$_2$ demonstrate that bulk-homogeneous defect concentrations in electrostructurally bistable materials can be tuned rapidly and deterministically by controlling applied electric current. Abruptly interrupting the current quenches the system into long-lived, room-temperature metastable states with distinct properties. This establishes a practical, rapid, and scalable pathway for defect engineering with direct relevance to nonvolatile memory devices.