Specific heat study of single-crystalline Pr<SUB>0.63</SUB>Ca<SUB>0.37</SUB>MnO<SUB>3</SUB> in presence of a magnetic field

We present the results of a study of the specific heat on a single crystal of Pr0.63Ca0.37MnO3 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 LCO≈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