Magneto-caloric effect in FeZrB amorphous alloys near room temperature

The magneto-caloric effect exhibited by three Fe-rich FeZrB amorphous alloys with different compositions and Curie temperatures between 230 and 300 K has been studied. Albeit the maximum entropy change is low (|ΔSM|max ∼ 3 J kg−1 K−1 under an applied magnetic field change from 0 to 50 kOe), the magneto-caloric effect (MCE) spreads out over a broad temperature interval (ΔT ∼ 200 K). The estimated values for the relative cooling power are close to that of pure Gd. From the applied magnetic field dependence of the magnetic entropy change a master curve valid for these Fe-rich FeZrB amorphous alloys has been found. However, two reference temperatures of the |ΔSM|(T) are needed in order to get a collapsing curve for all the maximum applied magnetic field values. The latter suggests that the striking magnetic behaviour of these compounds below 200 K influences the MCE effect. Moreover, the collapse into the same curve for different rescaled temperature dependences of the magnetic entropy change in the three samples implies the existence of similar magnetic interactions in these compounds.