Ion irradiation and implantation modifications of magneto-ionically induced exchange bias in Gd/NiCoO

Magneto-ionic control of magnetic properties through ionic migration has shown promise in enabling new functionalities energy-efficient spintronic devices. In this work, we demonstrate the effect helium ion irradiation and oxygen implantation on magneto-ionically induced exchange bias Gd/Ni$_{0.33}$Co$_{0.67}$O heterostructures. Irradiation using $He^+$ leads to an expansion Ni$_{0.33}$Co$_{0.67}$O lattice due strain relaxation. At low He+ fluence ($\leq$ 2$\times$10$^{14}$ ions cm$^{-2}$), redox-induced interfacial moment initially increases, owing enhanced migration. higher fluence, is suppressed reduction pinned uncompensated spins. For implanted samples, initial below a dose 5$\times$10$^{15}$ cm$^{-2}$ subsequently dominated at by contraction phase segregation into NiO CoO-rich phases, which turn alters bias. These results highlight possibility as effective means tailor magneto-ionic effects.