Magnetic properties and magnetocaloric effect in NdCo2B2 compound

The magnetic properties and magnetocaloric effect (MCE) of NdCo2B2 were investigated by magnetization and heat capacity measurements. The compound exhibits a paramagnetic to ferromagnetic transition at T-C = 27 K. The effective magnetic moment is 3.53 mu(B)/Nd atom, and the magnetic ground state of Nd ion forms a doublet state in NdCo2B2. A large reversible MCE was observed, which is related to a second-order magnetic transition from the paramagnetic to the ferromagnetic state. The values of maximum magnetic entropy change (-Delta S-M(max)) reach 4.5 and 8.3 J kg(-1) K-1 for field changes of 20 and 70 kOe without obvious hysteresis loss in the vicinity of the Curie temperature, respectively. The corresponding maximum adiabatic temperature changes (Delta T-ad(max)) are evaluated to be 3.3 and 6.9 K.