Magnetic entropy calculation for a second-order ferromagnetic phase transition.

In this paper, we present a new calculation method of magnetic entropy in an arbitrary second-order ferromagnetic phase transition system. Based on the Arrott-Noakes relation (H/M)1/γ = (T-TC)/TC+(M/M1)1/β, the Gibbs energy can be rewritten as a new form where the critical exponents are naturally included. Correspondingly, the magnetic entropy (SM) is presented as: . Thus, the magnetic entropy change (ΔSM) can be deduced as which is consistent exactly with the previous report [V. Franco et al., Appl. Phys. Lett. 89 (2006) 222512]. In addition, the conventional calculation method of magnetic entropy can be treated as a particular form of this calculation method. Furthermore, the obtained magnetic entropy change from experimental measurement are consistent with the theoretical value deduced from the present method. [ABSTRACT FROM AUTHOR]