Magnetocaloric effect and critical behavior of amorphous (Gd4Co3)1−xSix alloys

Abstract

The amorphous alloys (Gd4Co3)1−xSix (x=0, 0.05, and 0.10) were prepared by melt spinning. The Curie temperature can be tuned from 213 to 198K with increasing Si content, while the maximum value of magnetic entropy change for a magnetic field change of 0–5T can reach 7.3, 7.2 and 6.4Jkg−1K−1 for x=0, 0.05 and 0.10 respectively. Large values of the refrigerant capacity are obtained in these alloys. The saturation magnetization at 5K equals 26.5μB, 24.2μB and 22.4μB per (Gd4Co3)1−xSix formula with x=0, 0.05 and 0.10, respectively. All samples undergo a second order ferri–paramagnetic phase transition. The critical behavior around the transition temperature is investigated by means of the modified Arrott plots technique, the Kouvel–Fisher method and the Widom scaling relation. The results indicate that for x=0 and 0.05, the critical exponents are close to those of the 3D Ising model, while the critical exponents for x=0.1 are between those of the 3D Ising model and mean-field model.