Specific heat study of single-crystalline Pr_0.63Ca_0.37MnO₃ in presence of a magnetic field

Abstract

We present the results of a study of the specific heat on a single crystal of Pr_0.63Ca_0.37MnO₃ performed over a temperature range 3-300 K in the presence of 0 and 8 T magnetic fields. An estimate of the entropy and latent heat in a magnetic field at the first-order charge-ordering (CO) transition is presented. The total entropy change at the CO transition, which is ≈1.8 J/mol K at 0 T, decreases to ~1.5 J/mol K in the presence of a 8 T magnetic field. Our measurements enable us to estimate the latent heat L_CO≈235 J/mol involved in the CO transition. Since the entropy of the ferromagnetic metallic (FMM) state is comparable to that of the charge-ordered insulating state, a subtle change in entropy stabilizes either of these two states. Our low-temperature specific heat measurements reveal that the linear term is absent at 0 T and surprisingly not seen even in the metallic FMM state.