Irradiation driven magnetism enhancement in Y-doped HfO2 films

HfO2-based ferroelectric films are regarded as core materials for next-generation non-volatile memories and spintronics owing to their CMOS compatibility and exceptional ferroelectricity. Yet, the minute energy differences between polymorphs and the intricate defect-structure coupling have impeded precise, quantitative control of their ferroelectric and magnetic properties. Here, we introduce a non-equilibrium γ-ray irradiation strategy to modulate the magnetic response of 7% Y-doped epitaxial HfO2 thin films. Correlated structural, spectroscopic, and magnetic analyses reveal a nonlinear correlation between oxygen vacancies and lattice distortions. At an intermediate dose of 260 Gy, cooperative compressive strain and engineered vacancies boost out-of-plane saturation magnetization by 480%. Conversely, at 4800 Gy, excessive defect accumulation drives structural degradation and suppresses magnetism. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning transmission electron microscopy jointly track the evolution of defect and lattice structure, elucidating a dose-dependent crossover from defect-driven magnetism enhancement to quenching governed by competitive defect-structure interactions. The work establishes a dose-defect-magnetism framework and provides a route toward magneto-electric cooperative control of wide-bandgap oxides for spintronic applications.