An experimental and theoretical study of magnetocaloric effect in Nd_0.5Dy_0.5FeO₃

A significant magnetocaloric effect (MCE) has been revealed in our investigation on polycrystalline Nd_0.5Dy_0.5FeO₃ below 30 K. Observed magnetization of the system at low temperature is 32% higher than the expected average magnetization of NdFeO₃ and DyFeO₃. Such an enhancement in the magnetization led to a large change in magnetic entropy (10.4 Jkg^-1 K^-1) at 4 K. The observed entropy change is remarkable considering the higher natural abundance of Nd compared to that of Dy and negligible MCE seen in case of NdFeO₃. Theoretical calculations performed using mean-field approximation and Monte Carlo simulations on an Ising type spin model indicate that the high magnetocaloric effect is caused primarily by the ordering of rare-earth ions in C-type antiferromagnetic state in presence of molecular exchange field created by Fe ions.