Utilization of high entropy in rare earth-based magnetocaloric metallic glasses

In this study, the magnetic behavior and magnetocaloric effect (MCE) of Dy18Er18Y18Ni26Al20 and Dy13.5Er13.5Y13.5Gd13.5Ni26Al20 high-entropy bulk metallic glasses (BMGs) were systematically investigated, as well as Dy27Er27Ni26Al20 and Dy54Ni26Al20 medium-entropy BMGs. Distinct spin glass-like behavior below the Curie temperature and large MCE at cryogenic temperature were observed in all BMGs. Competitive magnetic entropy change values of 10.6 and 10.2 J kg−1K−1 were obtained for the Dy27Er27Ni26Al20 and Dy18Er18Y18Ni26Al20 BMGs, respectively, under a magnetic field change of 5 T. Accordingly, the effect of configuration entropy on the magnetic response and MCE was discussed. It was found that the magnetic phase transition temperature, magnetic hysteresis and refrigeration capacity can be altered by utilization of configuration entropy, which can be ascribed to the change in random magnetic anisotropy and magnetic interactions. However, no distinct difference in the magnetic entropy change was observed from the ternary Dy54Ni26Al20 to senary Dy13.5Er13.5Y13.5Gd13.5Ni26Al20 BMGs with increasing configuration entropy. The results reveal that the typical cocktail effect of high-entropy alloys is not applicable to magnetic entropy changes in these BMGs. Nevertheless, all BMGs in this study show good glass-forming ability and MCE which make them promising refrigerant candidates at cryogenic temperatures.