Pf-hybridization and magnetic phase transitions in ferromagnetic superconductors

Abstract In the framework of the Anderson pf-model, magnetic phase transitions in 5f-ferromagnetic superconductors with hybridization of localized (f-) and delocalized (p-) electrons are discussed. We consider a free-energy functional containing a contribution due to the mode-mode coupling spin fluctuations. The calculated p-T-diagram of magnetic states describes transitions of the first and second order and the region of the ferromagnetic short-range order too. It is shown that when the temperature and pressure change, a shift of the chemical potential to the pseudogap region is possible, with a jump-like increase in the occupation of the spin-symmetrized electronic states and an increase in the screening of the local magnetic moments.