We report on the first-order reversal curves (FORC) of magnetization and effect of defects on magnetization process in Fe71Ga29 thin films with different values of sputtering power (50 – 120 W). Phase purity of the thin films was confirmed by grazing incidence X– ray diffraction (GI-XRD). The reversible and irreversible contributions to the magnetization are evidenced through the minor loop parameter such as pseudo hysteresis loss (WF*) and energy loss coefficient (WF0). In particular, the energy loss coefficient is found to decrease from 28 × 106 (A/m. mT) at 50 W to 21 × 106 (A/m. mT) at 120 W, which signifies a decrease in domain wall resistance. FORC infers narrow switching, which leads to low coercivity distribution at 120 W as a result of less defects. © 2021