Magnetic Heat Capacity of Monoclinic (La0.8Ca0.2)MnO3

Abstract

Heat capacity of (La _0.8 Ca _0.2 )MnO ₃ was measured by a laser-flash method. An anomaly of the heat capacity with the entropy change of Δ S =0.54 cal/mol ·K was observed near magnetic transition temperature T _c . By assuming a simple Heisenberg model, an exchange interaction constant was determined to be J =8.0 cal/mol. The value of the magnetic heat capacity at T _c was Δ C =4.2 R , which is nearly equal to the value calculated from a double exchange model. The analysis of the heat capacity near T _c showed clearly that the transition is of second order and induced only by the change of electronic state.