The study of thermal properties of f-electron systems in the ferromagnetic state

The rare earth and actinide series of compounds display anomalous physical properties below a characteristic low temperature with very high specific heat coefficient and high effective mass. Here we consider the periodic Anderson model with the repulsive electron-electron interaction within mean-field approximation leading to ferromagnetism in the system. We calculate conduction electron as well as f-electron Green's functions by using Zubarev's Green's function technique and calculate ferromagnetic magnetisation numerically and self consistently. The thermal properties like the temperature dependent entropy, specific heat coefficient and electronic specific heat are calculated from the electron free-energy of the f-electron system and are computed numerically. The specific heat coefficient displays high value in heavy fermion state of the system where the position of the f-electron level is away from the Fermi level with the lower strength of hybridisation between f and conduction electrons.