Effect of Tm substitution on the magnetic and magnetocaloric properties in the intermetallic compounds (Tb_1-xTm_x)Co₂

The magnetic and magnetocaloric properties of the intermetallic compounds Tb_1-xTm_xCo₂ (with x ≤ 0, 0.2 and 0.5) have been studied. It is found that partial replacement of Tb by Tm in TbCo ₂ leads to a reduction in the ordering temperature, which is attributed to the decrease in the exchange strength due to the lower spin value of Tm³⁺ as compared with that of Tb³⁺. The analysis of the zero-field heat capacity data at low temperature shows that the coefficient of electronic heat capacity increases with increase in Tm content and is attributed to the presence of local spin fluctuations. The variation of the magnetocaloric effect (MCE) has been explained on the basis of the magnetic properties. Temperature dependence of the MCE shows that this system may be useful for magnetic refrigeration applications in a sub-room temperature regime.