Jeong, Jaegyu Jang, Bogeun Lee, Yeonhee Jang, Yunjung Hong, Jongill 2026-01-13T07:30:05Z 2026-01-13T07:30:05Z 2026-01-12 2026-03 0169-4332 https://pubs.kist.re.kr/handle/201004/153986 Low-energy hydrogen-ion irradiation provides a non-destructive, precise route to tailor materials by modifying bulk and interfacial structures, enabling the conversion of paramagnetic oxides to ferromagnetic metals with minimal damage. We apply this approach to CoO/Pd multilayers, achieving reduction to Co/Pd while elucidating the mechanism. Deuterium is employed to isolate hydrogen-specific effects. The saturation magnetization increases with acceleration energy, indicating a progressive CoO → Co transformation driven by oxygen-vacancy-mediated out-diffusion. Depth-resolved chemical profiling, compared with simulations of defect production, reveals an energy-dependent crossover: at lower energies, dissociation of OH species supplies oxygen that diffuses out; at higher energies, direct oxygen removal dominates. X-ray reflectivity shows that smoother, more uniform interfaces promote oxygen out-diffusion and thereby accelerate reduction. Together, these results establish sub-keV hydrogen-ion irradiation as a controllable, non-destructive tool for nanoscale physicochemical phase control and for coupled tuning of bulk and interface states. Beyond the CoO/Pd system, the ability to program magnetic properties within a single heterostructure by energy modulation highlights opportunities for spintronic thin films and device-relevant surface engineering. English Elsevier BV Physicochemical reduction of CoO to metallic Co by non-destructive, low-energy hydrogen-ion irradiation Article 10.1016/j.apsusc.2025.165610 1 Applied Surface Science, v.723 Applied Surface Science 723 N scopus 001648871900001 2-s2.0-105025189944 Chemistry, Physical Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Chemistry Materials Science Physics Article ANISOTROPY Low-energy proton irradiation Physicochemical reduction Co/Pd multilayer Oxygen diffusion Ferromagnetism