Magnetocaloric effect in the Ce2Fe17−xMnx helical magnets

The Ce₂Fe_17−xMn_x (x = 0-2) compounds demonstrate a complex temperature dependence of the magnetocaloric effect MCE, which is inverse in a narrow temperature interval just below Néel temperature T_N and normal at higher or lower temperatures. The normal MCE exhibits two peaks in the vicinity of temperatures of ferromagnetic ordering Θ_T and T_N for compositions x = 0-0.35, 1.3-2 or one peak near T_N for antiferromagnets with x = 0.5-1. The maximal change of the peak entropy −S_M is about 3 J/kg K in a field of 5 T for the compounds with x = 0-0.5 at T ∼230 K close to T_N. The drastic decrease of the MCE, by half, in the Ce₂Fe_17−xMn_x system is traceable to a decrease of the spontaneous magnetization and the helical type of magnetic states in the compounds.