Critical behavior and magnetocaloric effect in layered structure Tb₂C

The critical behavior and magnetocaloric effects of the layered structure Tb₂C have been investigated using magnetization measurements around the Curie temperature. Analyzing temperature and field dependence of magnetization reveals that the Tb₂C system undergoes a second-order magnetic phase transition at T _C  =  266 K. Critical exponents obtained from modified Arrott, Kouvel–Fisher (KF) and scaling plots are consistent with each other. The critical exponents suggest that the magnetic phase transition in Tb₂C can be described by the mean-field model. The exchange energy declines as J ( r ) ∼ r ^−4.547, indicating that long-range interaction dominates the exchange interaction. Consequently, the field dependence magnetic entropy change (Δ S _M) of Tb₂C, calculated using the Maxwell relation, clearly demonstrates that the relationship between  −Δ S _M and ( H / T _C)^2/3 obeys the mean-field theory, supporting our conclusion of the ferromagnetism phase transition in Tb₂C following the mean-field theory. (paper)