A phenomenological theory for the double-peak structure in the specific heat of CeRu\(_{2}\)Si\(_{2}\)

Abstract

The double-peak structure observed in the specific heat of CeRu\(_{2}\)Si\(_{2}\) is explained by a phenomenological theory with free energy density expansion by entropy deviation within the first and third order. We minimize this free energy density with respect to the entropy deviation and obtain the specific heat of CeRu\(_{2}\)Si\(_{2}\). The critical behavior of the specific heat as a function of the external magnetic field is also obtained within this theory. However, since this critical behavior would be an artifact of the mean-field theory, this criticality should be weakened in a desirable theory. Compared with an experiment, the temperature dependence of the peak value of the specific heat is also determined.