Entropy change at the magnetostructural transition in RCo2(R=Dy,Ho,Er)

Differential scanning calorimetry under applied magnetic field has been used to characterize the magnetocaloric effect in ErCo2ErCo2, HoCo2HoCo2, and DyCo2DyCo2. The entropy change ΔSΔS at the first-order magnetostructural transition present in these materials has been studied by inducing the transition; sweeping the temperature at a constant field and sweeping the field at a constant temperature. The corresponding values of ΔSΔS differ significantly due to the broadness of the transition, i.e. the initial and final states involved when the transition is field or temperature induced are different. In the field-induced case, the additional work done by the magnetic field extending through the region in which the transition spread accounts roughly for the observed difference.