Magnetic phase transitions and magnetocaloric effect in ternary rhombohedral Laves phases of Gd2Rh3Ge and Er2Rh3Ge

Abstract Magnetic phase transitions in two Mg 2 Ni 3 Si -type of Gd2Rh3Ge and Er2Rh3Ge compounds (space group R 3 ‾ m , hR18) belonging to rhombohedral Laves phases are studied in this paper. Structural investigations using X-ray diffraction and subsequent Rietveld analysis confirm the rhombohedral R 3 ‾ m Laves phase for both compounds. Magnetization as a function of temperature, M ( T ) , identifies the ferromagnetic transition temperature in both samples with T C = 64 K and 20 K for Gd2Rh3Ge and Er2Rh3Ge respectively which is supported by the specific heat, C p ( T ) . Arrott plots, universal scaling curves by normalizing magnetic entropy changes ( Δ S m ) and field dependent Δ S m revealed that both compounds undergo second order ferromagnetic phase transitions at T C . Significant magnetocaloric effect (MCE) is observed for both compounds, attaining a value of 12 J kg-1 K-1 at T = 64 K, H = 7 T for Gd2Rh3Ge and 11 J kg-1 K-1 at T = 20 K, H = 7 T for Er2Rh3Ge. The adiabatic temperature change is 5.9 K for Gd2Rh3Ge and 10.5 K for Er2Rh3Ge for H = 7 T.