Voltage Control of Patterned Metal/Insulator Properties in Oxide/Oxyfluoride Lateral Perovskite Heterostructures via Ion Gel Gating

Dynamic control of patterned properties in perovskite oxide films can enable new architectures for electronic, magnetic, and optical devices. In this study, it is shown that SrFeO_3-δ/SrFeO₂F laterally-heterostructured films enable voltage-controlled tunable and reversible metal-insulator patterned properties using room-temperature ion gel gating. Specifically, SrFeO_3-δ film regions can be toggled between insulating H_xSrFeO_2.5 and metallic SrFeO₃ by electrochemical redox, while SrFeO₂F regions remain robustly insulating and are unaffected by ion gel gating. Various gating architectures are also compared and establish the advantages of employing a conductive substrate as the contacting electrode, as opposed to at the film surface, thereby achieving complete and reversible reduction and oxidation among SrFeO_3-δ, H_xSrFeO_2.5, and SrFeO₃. This approach to voltage-modulated patterned electronic, optical, and magnetic properties should be broadly applicable to oxide materials amenable to fluoridation, and potentially other forms of anion substitution.