Ionic Pathways to Neuromorphic Function: Direct Visualization of Oxygen Migration in Interface Synaptic Memristive Devices

. Our results establish that co-doping not only stabilizes oxygen vacancies but also facilitates interfacial oxygen migration, enabling tunable, multilevel conductance states and reliable synaptic plasticity in oxide-based memristors, which these dynamics directly visualized via in-operando optical spectroscopies. By correlating electrical performance with Raman, photoluminescence, and dark-field signatures, this work provides the first direct, cycle-resolved evidence linking interface and defect engineering to controllable ionic motion and emergent neuromorphic functionality, highlighting a general strategy for designing high-endurance, optically trackable memristive devices.