Atomic-Resolution Mapping of Electric Fields and Strain across Single-Crystalline/Amorphous Interfaces

Amorphous/crystalline interfaces that combine structural distortion with local charge redistribution remain poorly understood, mainly owing to limited access to atomically well-defined single-crystalline components and correlative probes of interfacial fields. Herein, we construct atomically resolvable single-crystalline/amorphous heterointerfaces by synthesizing a library of transition metal oxytellurides and map the projected electric field and strain by combining scanning transmission electron microscopy (STEM) with four-dimensional STEM (4D-STEM). In RuTe_1.93O_0.97, 4D-STEM reveals a locally enhanced electrostatic field whose direction reorients at the interface. Charge density maps show electron accumulation in the amorphous region and depletion in the single-crystalline region, suggesting directional electron transfer. Nanometer-scale tensile and compressive strain localized around the heterointerface is identified. Electronic structure calculations indicate enhanced Ru 4d delocalization near the Fermi level, facilitating electron-driven reactions. This work spatially correlates atomic structure with built-in electric fields and lattice strain at disordered-ordered interfaces, providing a general route to elucidating structure-activity relationships.