Controlled modification of perpendicular magnetic anisotropy in Pt/Gd–Fe/Ta trilayers via electron beam irradiation

Abstract The pursuit of high-density magnetic storage has been a driving force behind the development of magnetic storage media with perpendicular magnetic anisotropy (PMA). Achieving precise control over PMA necessitates highly tunable modification techniques that are compatible with modern electronic device fabrication processes. In this work, we demonstrate a depth-selective and controllable modification of PMA in Pt/Gd–Fe/Ta trilayers with Gd–Fe thicknesses of 10 nm, 15 nm, and 20 nm using high-energy (1 MeV) electron beam irradiation (EBI). Structural characterization by scanning transmission electron microscopy reveals irradiation-induced atomic intermixing, defect formation, and interface modification throughout the trilayer stack. Magnetic measurements show a pronounced enhancement of out-of-plane coercivity relative to the in-plane (IP) direction for all irradiated films, indicating strengthened PMA. Magnetic force microscopy reveals checkerboard-like domain patterns across all samples, with an increase in average domain size of approximately 100 nm after irradiation. Angular-dependent magneto-optical Kerr effect measurements confirm the presence of fourfold IP anisotropy, consistent with the Fe-rich composition of the Gd–Fe layer, while a post-irradiation tilt in the polar plots indicates a reorientation of the effective anisotropy axis driven by strain relaxation, in agreement with grazing-incidence x-ray diffraction results. These findings establish EBI as an effective, depth-sensitive approach for engineering magnetic anisotropy in ferrimagnetic heterostructures, offering promising opportunities for advanced spintronic and magnetic memory applications.