Comparative study of the specific heat and chemical potential at phase transitions

The temperature dependence is studied of the specific heat and chemical potential using the model describing phase transitions from ferromagnet to paramagnet, from superconductor to normal system, as well as, combined reentrant phase transitions (normal ferromagnet–superconducting ferromagnet–paramagnetic superconductor–normal paramagnet). In the case of the phase transitions: ferromagnet–paramagnet or superconductor–normal system, the shapes of the temperature dependence of the specific heat and the temperature derivative of the chemical potential are similar with characteristic jump at the critical temperature. For the reentrant type phase transitions the upper superconducting critical temperature is hardly seen in the specific heat plot (exactly the same situation takes place in the experiment). The chemical potential temperature dependence locates, however, with ease this critical point. This observation can be widely utilized in the experimental praxis to locate precisely all critical points with the use of the chemical potential measurements, especially in such cases where other methods fail.