Searching the conditions for a table-like shape of the magnetic entropy in magneto-caloric materials

Highlights: •The magnetic entropy change for two-ribbon (amorphous) composite materials is investigated. •The conditions to obtain a table-like shape of the magnetic entropy change are specified. •We give the essential ingredients to maximize the effective refrigerant capacity and the efficiency. •Our findings could be used in other magneto-caloric materials to tune the temperature range for the table-like behavior. -- Abstract: We show a systematic study of the magneto-caloric response carried out on a series of FeZrB(Cu) amorphous ribbons with different Curie temperature values in the 210–320 K interval. The main aim of the work is to investigate the conditions to obtain, from the isothermal magnetic entropy change vs. temperature curves, ΔSM(T), a table-like behavior of the entropy using two-ribbon composites. Even though the maximum value of ΔSM for the composite is lower than those of the single components, the existence of a table-like behavior maximizes the effective refrigerant capacity, reaching values around 80 J/kg for an applied magnetic field change of 2 T. Furthermore, we discuss how the temperature range for such a table-like behavior can be tuned and the refrigerant capacity enhanced in terms of energy efficiency