Specific heat anomaly due to valence transition in Eu(Pd1−xPtx)2Si2

Specific heat was measured for Eu(Pd1−xPtx)2Si2 with 0≤x≤0.10, in which the Eu valence sharply varies with temperature. A large specific heat peak due to the valence change was observed in each compound. Using the specific heat of LaPd2Si2 as a normal part, we estimated the entropy associated with valence transition. It was found that the entropy increases abruptly around the valence transition temperature and reaches a saturation value of 22–23 J/K mol at room temperature. The temperature dependence of the entropy associated with the valence transition was calculated in terms of the interconfigurational fluctuation (ICF) model. We will demonstrate that the experimental results are well described by the ICF model.