Magnetic entropy change in GdCo13−xSix intermetallic compounds

The magnetic entropy change in GdCo13−xSix (x=3.8, 4, 4.1, and 4.2) intermetallic compounds has been investigated by means of magnetic measurements in the vicinity of their Curie temperature. It was found that the magnetic ordering temperatures decrease from 60 K at x=3.8 to 28 K for x=4.2. The magnetic entropy change is calculated from isothermal magnetization versus magnetic field at various temperatures using the Maxwell relation. As a result, the maximum magnetic entropy changes of the investigated compounds, at their Curie temperatures, decrease from 11.5 J/kg K for x=4.2 to 6.86 J/kg K for x=3.8 in a field change of 0–3 T, whereas it decreases from 5.13 J/kg K for x=4.2 to 2.60 J/kg K for x=3.8 in a field change of 0–1 T. Moreover, the maximum value of the magnetic entropy change obtained at a higher field for GdCo13−xSix with x=4 (23.75 J/kg K at 5 T) is comparable to that of various types of compounds with a cubic NaZn13-type structure. Finally, the maximum of the magnetic entropy change is found to decrease with increasing Si content.