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

• 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.

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.

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