Tuning nanoscale heterogeneity by non-affine thermal strain to modulate defect activation and maximize magnetocaloric effect of metallic glass

•Rejuvenation, increased structure order, and nanocrystallization induced by proper cryogenic thermal cycling are observed.•Two kinds of flow defects with different relaxation times are detected by using the Maxwell-Voigt model.•An apparent enhancement of the maximum magnetic entropy change from 9.5 to 10.7 JKg-1K−1 under 5 T is obtained.•A power law between the peak temperature and maximum magnetic entropy change is revealed above 85 K.