Assessment of the magnetocaloric effect in La,Pr(Fe,Si) under cycling

The response of a magnetocaloric material to periodic variations of magnetic field and temperature corresponding to those occurring during a magnetic refrigeration process is studied. A series of simple measurement protocols are suggested which are used to obtain a value for the cyclic response of the magnetic entropy change associated with the magnetic transition. The entropy values are compared to direct measurements of the temperature change under adiabatic conditions . The procedure is illustrated on the first order magnetocaloric material La 0.6 Pr 0.4 Fe 11.6 Si 1.4 and provides a basis for comparison of the suitability of different hysteretic magnetocaloric materials for application in a magnetic refrigerator. For the alloy studied here the peak magnetic entropy change of −28±1 J kg −1 K −1 in a field change of 2 T is not affected by cycling, but the full width at half maximum of the peak decreases from 8.7 K to 3.8 K.