Swift heavy ion irradiation induced structural, morphological, and magnetic characteristics of FeGaB magnetic thin films

Abstract This study focuses on the effect of electronic excitation induced by swift heavy ion (SHI) irradiation on the structural, morphological, and magnetic properties of FeGaB thin films deposited on an Al 2 O 3 (0001) single crystal substrate via radio frequency magnetron sputtering. The FeGaB films were irradiated with 140 MeV Ag 11+ ions at three different fluences: 1 × 10 11 , 1 × 10 12 , and 1 × 10 13 ions cm −2 . The x-ray diffraction patterns and field emission scanning electron microscope images confirm that SHI irradiation promotes the crystallization of amorphous FeGaB films. Magnetization studies using vibrating sample magnetometer reveal that the squareness ratio, coercivity and saturation magnetization of films are modified substantially with the SHI irradiation. The squareness ratio improves from 0.16 to 0.35, while the coercivity decreases from 60 Oe in pristine film to 18 Oe at the optimum fluence of 1 × 10 12 ions cm −2 . The reversible temperature-dependent magnetization curves, measured under zero-field-cooled (ZFC) and field-cooled (FC) conditions, indicate a reduction in magnetic anisotropy at this fluence. The changes observed in magnetic properties are attributed to strain relaxation, grain refinement, and defect generation induced by ion impact. Overall, this study examines the sensitivity of FeGaB thin films to SHI irradiation, thereby exploring the potential of FeGaB-based magnetoelectric devices for deployment in radiation zones.