Near‐Field Nanoimaging of Programmable Phase Transitions in Ga + ‐Irradiated VO 2

ABSTRACT Developing quantum materials for electronic devices, including neuromorphic computing, is a rapidly expanding field. Vanadium dioxide (VO 2 ) is a prototypical correlated oxide known for its sharp, reversible insulator‐to‐metal transition (IMT), making it a compelling platform for reconfigurable electronics. Controlled defect formation, such as focused Ga + ion beam irradiation, can influence the IMT in VO 2 , yet the associated nanoscale phase behavior and switching mechanisms remain largely unexplored. Here we introduce spatially localized defects in VO 2 using focused Ga + irradiation with tunable dose and probe the resulting thermal‐ and voltage‐driven IMT using infrared and terahertz near‐field nano‐imaging. Focused Ga + irradiation alters, and often suppresses, phase switching behavior, localizing the conductive pathway and reducing switching power for energy‐efficient neuromorphic functionality. Compared to pristine VO 2 , the irradiated material exhibits suppressed IMT behavior, with lower resistivity below the transition temperature but higher resistivity above it. Varying irradiation dose modulates this suppression, impacting filamentary nucleation. Devices with lightly irradiated regions localize the resistive switching behavior, whereas heavily irradiated regions remained inactive during switching, with neighboring pristine material switching into the metallic phase instead. These findings reveal selective ion irradiation enables local control of the IMT in VO 2 , offering a scalable route to programmable, energy‐efficient neuromorphic devices.